diff --git a/app/assets/stylesheets/sidebar.scss b/app/assets/stylesheets/sidebar.scss
index 4306371f10..0e1b9e1dcb 100644
--- a/app/assets/stylesheets/sidebar.scss
+++ b/app/assets/stylesheets/sidebar.scss
@@ -89,12 +89,19 @@ body:has(.bops-fullwidth-container) {
   width: 100%;
 }
 
-.bops-sidebar__task {
+.bops-sidebar .govuk-list.govuk-list--spaced > .bops-sidebar__task {
   display: flex;
   align-items: center;
   gap: govuk-spacing(2);
-  padding-bottom: govuk-spacing(2);
+  padding: govuk-spacing(2) 20px;
+  margin: 0 -20px;
   border-bottom: 1px solid #8eb8dc;
+  border-left: 4px solid transparent;
+
+  &.bops-sidebar__task--active {
+    background-color: #d4e4f1;
+    border-left-color: $govuk-link-colour;
+  }
 }
 
 .bops-sidebar ul h3 {
diff --git a/app/components/sidebar_component.rb b/app/components/sidebar_component.rb
index cf6d55b55e..5ccb0331e0 100644
--- a/app/components/sidebar_component.rb
+++ b/app/components/sidebar_component.rb
@@ -26,19 +26,23 @@ def render_task(task)
     if task.section.present?
       render_section(task)
     else
+      is_active = current_task?(task)
       target = if task.legacy_url.present?
         route_for(task.legacy_url, planning_application)
       else
         BopsPreapps::Engine.routes.url_helpers.task_path(@case_record,
           slug: task.full_slug, reference: planning_application_reference)
       end
-      link = helpers.govuk_link_to(task.name, target)
+      link_options = is_active ? {"aria-current" => "page"} : {}
+      link = helpers.govuk_link_to(task.name, target, **link_options)
       content = if task.status_hidden?
         safe_join([invisible_status_placeholder, link], " ")
       else
         safe_join([status_indicator_for(task), link], " ")
       end
-      helpers.tag.li(content, class: "bops-sidebar__task")
+      li_classes = ["bops-sidebar__task"]
+      li_classes << "bops-sidebar__task--active" if is_active
+      helpers.tag.li(content, class: li_classes.join(" "))
     end
   end
 
@@ -74,4 +78,11 @@ def status_indicator_for(task)
   def invisible_status_placeholder
     helpers.content_tag(:span, "", class: "bops-sidebar__task-icon", aria: {hidden: true})
   end
+
+  def current_task?(task)
+    current_slug = params[:slug]
+    return false if current_slug.blank?
+
+    task.full_slug == current_slug
+  end
 end
diff --git a/engines/bops_preapps/app/forms/bops_preapps/tasks/check_red_line_boundary_form.rb b/engines/bops_preapps/app/forms/bops_preapps/tasks/check_red_line_boundary_form.rb
index 2101f50797..a3916823bc 100644
--- a/engines/bops_preapps/app/forms/bops_preapps/tasks/check_red_line_boundary_form.rb
+++ b/engines/bops_preapps/app/forms/bops_preapps/tasks/check_red_line_boundary_form.rb
@@ -3,9 +3,10 @@
 module BopsPreapps
   module Tasks
     class CheckRedLineBoundaryForm < Form
-      self.task_actions = %w[save_and_complete mark_as_valid]
+      self.task_actions = %w[save_and_complete mark_as_valid delete_request]
 
       attribute :valid_red_line_boundary, :boolean
+      attribute :validation_request_id, :integer
 
       with_options on: :save_and_complete do
         validates :valid_red_line_boundary, inclusion: {in: [true, false], message: "Select whether the red line boundary is correct"}
@@ -22,6 +23,8 @@ def update(params)
             save_and_complete
           when "mark_as_valid"
             mark_as_valid
+          when "delete_request"
+            delete_validation_request
           end
         end
       end
@@ -29,19 +32,34 @@ def update(params)
       def redirect_url(options = {})
         return return_to if return_to.present?
 
-        if valid_red_line_boundary
+        case action
+        when "delete_request"
           super
+        when "save_and_complete"
+          if valid_red_line_boundary
+            super
+          else
+            Rails.application.routes.url_helpers.new_planning_application_validation_validation_request_path(
+              planning_application,
+              type: "red_line_boundary_change"
+            )
+          end
         else
-          Rails.application.routes.url_helpers.new_planning_application_validation_validation_request_path(
-            planning_application,
-            type: "red_line_boundary_change"
-          )
+          super
         end
       end
 
       def validation_request
-        @validation_request ||= planning_application.red_line_boundary_change_validation_requests.open_or_pending.first ||
-          planning_application.red_line_boundary_change_validation_requests.closed.last
+        @validation_request ||= if validation_request_id.present?
+          planning_application.red_line_boundary_change_validation_requests.find(validation_request_id)
+        else
+          planning_application.red_line_boundary_change_validation_requests.open_or_pending.first ||
+            planning_application.red_line_boundary_change_validation_requests.closed.last
+        end
+      end
+
+      def cancel_url
+        route_for(:cancel_request, planning_application, validation_request_id: validation_request.id, task_slug: task.full_slug, only_path: true)
       end
 
       def flash(type, controller)
@@ -52,6 +70,8 @@ def flash(type, controller)
           controller.t(".check-red-line-boundary.success")
         when "mark_as_valid"
           controller.t(".check-red-line-boundary.mark_as_valid")
+        when "delete_request"
+          controller.t(".check-red-line-boundary.delete_request")
         end
       end
 
@@ -70,6 +90,13 @@ def mark_as_valid
           task.complete!
         end
       end
+
+      def delete_validation_request
+        transaction do
+          validation_request.destroy!
+          task.not_started!
+        end
+      end
     end
   end
 end
diff --git a/engines/bops_preapps/app/views/bops_preapps/tasks/check-and-validate/check-application-details/check-red-line-boundary/show.html.erb b/engines/bops_preapps/app/views/bops_preapps/tasks/check-and-validate/check-application-details/check-red-line-boundary/show.html.erb
index d3902a62a1..32a3a36e74 100644
--- a/engines/bops_preapps/app/views/bops_preapps/tasks/check-and-validate/check-application-details/check-red-line-boundary/show.html.erb
+++ b/engines/bops_preapps/app/views/bops_preapps/tasks/check-and-validate/check-application-details/check-red-line-boundary/show.html.erb
@@ -23,13 +23,15 @@
     <p class="govuk-body govuk-!-margin-top-4">Waiting for applicant response.</p>
 
     <% if @planning_application.not_started? %>
-      <p class="govuk-body">
-        <%= delete_confirmation_request_link(
-              @planning_application,
-              @form.validation_request,
-              classname: "govuk-link"
-            ) %>
-      </p>
+      <%= form_with url: @form.url, method: :patch, data: {confirm: "Are you sure you want to delete this request?"} do |f| %>
+        <%= f.hidden_field :task_action, value: "delete_request" %>
+        <%= f.hidden_field "#{@form.param_key}[validation_request_id]", value: @form.validation_request.id %>
+        <%= f.govuk_submit "Delete request", secondary: true %>
+      <% end %>
+    <% end %>
+
+    <% if @planning_application.invalidated? %>
+      <p><%= govuk_link_to "Cancel request", @form.cancel_url %></p>
     <% end %>
   <% elsif @form.validation_request.closed? && @form.validation_request.approved? %>
     <h2 class="govuk-heading-m">Red line boundary change approved</h2>
@@ -64,11 +66,20 @@
       <p><%= @form.validation_request.updated_at.to_fs %></p>
     </div>
 
-    <p>
-      <%= govuk_link_to "Request a new red line boundary change",
-            main_app.new_planning_application_validation_validation_request_path(@planning_application, type: "red_line_boundary_change"),
-            class: "govuk-body" %>
-    </p>
+    <h3 class="govuk-heading-s">Current red line boundary</h3>
+    <%= render "shared/location_map", locals: {geojson: @planning_application.boundary_geojson} %>
+
+    <%= form_with model: @form, url: @form.url do |form| %>
+      <%= form.govuk_error_summary %>
+      <%= return_to_hidden_field %>
+
+      <%= form.govuk_radio_buttons_fieldset :valid_red_line_boundary, legend: {text: "Is the red line boundary correct?"} do %>
+        <%= form.govuk_radio_button :valid_red_line_boundary, true, label: {text: "Yes"} %>
+        <%= form.govuk_radio_button :valid_red_line_boundary, false, label: {text: "No"} %>
+      <% end %>
+
+      <%= render "shared/task_submit_buttons", form: form, save_draft: false %>
+    <% end %>
   <% end %>
 <% else %>
   <p>This digital red line boundary was submitted by the applicant.</p>
diff --git a/engines/bops_preapps/app/views/bops_preapps/tasks/check-and-validate/check-tag-and-confirm-documents/review-documents/show.html.erb b/engines/bops_preapps/app/views/bops_preapps/tasks/check-and-validate/check-tag-and-confirm-documents/review-documents/show.html.erb
index 498c1df5ce..355a632f41 100644
--- a/engines/bops_preapps/app/views/bops_preapps/tasks/check-and-validate/check-tag-and-confirm-documents/review-documents/show.html.erb
+++ b/engines/bops_preapps/app/views/bops_preapps/tasks/check-and-validate/check-tag-and-confirm-documents/review-documents/show.html.erb
@@ -1,6 +1,6 @@
 <%= render "shared/task_header", task: @task %>
 
-<div id="check-tag-documents-tasks">
+<div id="check-tag-documents-tasks" data-controller="download" data-application-reference-value="<%= @planning_application.reference %>">
   <h2 class="app-task-list__section">
     Submitted documents
   </h2>
diff --git a/engines/bops_preapps/app/views/shared/_task_header.html.erb b/engines/bops_preapps/app/views/shared/_task_header.html.erb
index 5252b5f8dd..1736c39e7b 100644
--- a/engines/bops_preapps/app/views/shared/_task_header.html.erb
+++ b/engines/bops_preapps/app/views/shared/_task_header.html.erb
@@ -7,12 +7,6 @@
 <% if task.top_level_ancestor.section == "Assessment" %>
   <% add_parent_breadcrumb_link "Assessment",
        main_app.planning_application_assessment_tasks_path(task.case_record.planning_application) %>
-<% elsif task.top_level_ancestor.section == "Validation" %>
-  <% add_parent_breadcrumb_link "Validation",
-       main_app.planning_application_validation_tasks_path(task.case_record.planning_application) %>
-<% elsif task.top_level_ancestor.section == "Consultation" %>
-  <% add_parent_breadcrumb_link "Consultation",
-       main_app.planning_application_consultation_path(task.case_record.planning_application) %>
 <% end %>
 
 <% page_heading = heading || task.title %>
diff --git a/engines/bops_preapps/config/locales/en.yml b/engines/bops_preapps/config/locales/en.yml
index 9118182f74..6636fe87db 100644
--- a/engines/bops_preapps/config/locales/en.yml
+++ b/engines/bops_preapps/config/locales/en.yml
@@ -9,6 +9,9 @@ en:
         check-fee:
           cancel_request: Fee change request successfully cancelled
           failure: Fee change request could not be cancelled
+        check-red-line-boundary:
+          cancel_request: Red line boundary change request successfully cancelled
+          failure: Red line boundary change request could not be cancelled
     constraint_consultees:
       destroy:
         success: Consultee was removed from this constraint
@@ -163,6 +166,7 @@ en:
           success: Fee check was successfully saved
           update_request: Fee change request successfully updated
         check-red-line-boundary:
+          delete_request: Red line boundary change request successfully deleted
           failure: Please select whether the red line boundary is correct
           mark_as_valid: Red line boundary was successfully marked as valid
           success: Red line boundary check was successfully saved
diff --git a/engines/bops_preapps/spec/system/tasks/add_and_assign_consultees_spec.rb b/engines/bops_preapps/spec/system/tasks/add_and_assign_consultees_spec.rb
index f63f5d7755..514255e512 100644
--- a/engines/bops_preapps/spec/system/tasks/add_and_assign_consultees_spec.rb
+++ b/engines/bops_preapps/spec/system/tasks/add_and_assign_consultees_spec.rb
@@ -78,7 +78,7 @@
 
     expect(page).to have_link("Home")
     expect(page).to have_link("Application")
-    expect(page).to have_link("Consultation")
+    expect(page).not_to have_link("Consultation")
   end
 
   it "hides save buttons when application is determined" do
diff --git a/engines/bops_preapps/spec/system/tasks/check_fee_spec.rb b/engines/bops_preapps/spec/system/tasks/check_fee_spec.rb
index c649d2414f..346efe2f1f 100644
--- a/engines/bops_preapps/spec/system/tasks/check_fee_spec.rb
+++ b/engines/bops_preapps/spec/system/tasks/check_fee_spec.rb
@@ -149,6 +149,17 @@
     end
   end
 
+  it "highlights the active task in the sidebar" do
+    within ".bops-sidebar" do
+      click_link "Check fee"
+    end
+
+    within ".bops-sidebar" do
+      expect(page).to have_css(".bops-sidebar__task--active", text: "Check fee")
+      expect(page).to have_css("a[aria-current='page']", text: "Check fee")
+    end
+  end
+
   it "shows correct breadcrumb navigation" do
     within ".bops-sidebar" do
       click_link "Check fee"
@@ -156,7 +167,7 @@
 
     expect(page).to have_link("Home")
     expect(page).to have_link("Application")
-    expect(page).to have_link("Validation")
+    expect(page).not_to have_link("Validation")
   end
 
   context "when fee change validation request exists" do
diff --git a/engines/bops_preapps/spec/system/tasks/check_red_line_boundary_spec.rb b/engines/bops_preapps/spec/system/tasks/check_red_line_boundary_spec.rb
index 0f9a37f82c..a69153fb42 100644
--- a/engines/bops_preapps/spec/system/tasks/check_red_line_boundary_spec.rb
+++ b/engines/bops_preapps/spec/system/tasks/check_red_line_boundary_spec.rb
@@ -118,7 +118,7 @@
     expect(page).to have_content("Proposed red line boundary")
     expect(task.reload).to be_completed
 
-    click_link "Delete request"
+    click_button "Delete request"
 
     expect(page).to have_current_path("/preapps/#{planning_application.reference}/check-and-validate/check-application-details/check-red-line-boundary")
     expect(page).to have_content("Check the digital red line boundary")
@@ -157,6 +157,17 @@
     end
   end
 
+  it "highlights the active task in the sidebar" do
+    within ".bops-sidebar" do
+      click_link "Check red line boundary"
+    end
+
+    within ".bops-sidebar" do
+      expect(page).to have_css(".bops-sidebar__task--active", text: "Check red line boundary")
+      expect(page).to have_css("a[aria-current='page']", text: "Check red line boundary")
+    end
+  end
+
   it "shows correct breadcrumb navigation" do
     within ".bops-sidebar" do
       click_link "Check red line boundary"
@@ -164,7 +175,7 @@
 
     expect(page).to have_link("Home")
     expect(page).to have_link("Application")
-    expect(page).to have_link("Validation")
+    expect(page).not_to have_link("Validation")
   end
 
   it "hides the draw red line boundary task when boundary_geojson is present" do
@@ -302,12 +313,46 @@
       expect(page).to have_content("The garage is not part of my property")
     end
 
-    it "shows link to request new red line boundary change" do
+    it "shows Yes/No form to re-check the boundary" do
+      within ".bops-sidebar" do
+        click_link "Check red line boundary"
+      end
+
+      expect(page).to have_field("Yes")
+      expect(page).to have_field("No")
+      expect(page).to have_button("Save and mark as complete")
+    end
+
+    it "marks boundary as valid and completes task when selecting Yes" do
+      expect(task.reload).to be_action_required
+
+      within ".bops-sidebar" do
+        click_link "Check red line boundary"
+      end
+
+      choose "Yes"
+      click_button "Save and mark as complete"
+
+      expect(page).to have_content("Red line boundary check was successfully saved")
+      expect(task.reload).to be_completed
+      expect(planning_application.reload.valid_red_line_boundary).to be true
+    end
+
+    it "redirects to new validation request when selecting No" do
+      expect(task.reload).to be_action_required
+
       within ".bops-sidebar" do
         click_link "Check red line boundary"
       end
 
-      expect(page).to have_link("Request a new red line boundary change")
+      choose "No"
+      click_button "Save and mark as complete"
+
+      expect(page).to have_current_path(
+        "/planning_applications/#{planning_application.reference}/validation/validation_requests/new?type=red_line_boundary_change"
+      )
+      expect(task.reload).to be_in_progress
+      expect(planning_application.reload.valid_red_line_boundary).to be false
     end
   end
 
@@ -364,6 +409,65 @@
     end
   end
 
+  context "when application is invalidated with open validation request" do
+    let(:new_geojson) do
+      {
+        type: "Feature",
+        properties: {},
+        geometry: {
+          type: "Polygon",
+          coordinates: [
+            [
+              [-0.054600, 51.537335],
+              [-0.054590, 51.537290],
+              [-0.054455, 51.537315],
+              [-0.054600, 51.537335]
+            ]
+          ]
+        }
+      }
+    end
+
+    let!(:validation_request) do
+      create(:red_line_boundary_change_validation_request,
+        :open,
+        planning_application:,
+        reason: "Boundary needs to include garage",
+        new_geojson: new_geojson,
+        original_geojson: boundary_geojson)
+    end
+
+    before do
+      task.complete!
+      planning_application.update!(status: "invalidated")
+    end
+
+    it "shows cancel link when application is invalidated" do
+      within ".bops-sidebar" do
+        click_link "Check red line boundary"
+      end
+
+      expect(page).to have_link("Cancel request")
+      expect(page).not_to have_button("Delete request")
+    end
+
+    it "allows cancelling the validation request" do
+      within ".bops-sidebar" do
+        click_link "Check red line boundary"
+      end
+
+      click_link "Cancel request"
+
+      expect(page).to have_content("Cancel validation request")
+
+      fill_in "Explain to the applicant why this request is being cancelled", with: "Boundary was correct after all"
+      click_button "Confirm cancellation"
+
+      expect(page).to have_content("Red line boundary change request successfully cancelled")
+      expect(validation_request.reload).to be_cancelled
+    end
+  end
+
   context "when applicant responds to red line boundary change request" do
     let(:new_geojson) do
       {
diff --git a/engines/bops_preapps/spec/system/tasks/determine_consultation_requirement_spec.rb b/engines/bops_preapps/spec/system/tasks/determine_consultation_requirement_spec.rb
index 7411a44aaf..a16c633b85 100644
--- a/engines/bops_preapps/spec/system/tasks/determine_consultation_requirement_spec.rb
+++ b/engines/bops_preapps/spec/system/tasks/determine_consultation_requirement_spec.rb
@@ -81,7 +81,7 @@
 
     expect(page).to have_link("Home")
     expect(page).to have_link("Application")
-    expect(page).to have_link("Consultation")
+    expect(page).not_to have_link("Consultation")
   end
 
   it "hides save button when application is determined" do
diff --git a/engines/bops_preapps/spec/system/tasks/draw_red_line_boundary_spec.rb b/engines/bops_preapps/spec/system/tasks/draw_red_line_boundary_spec.rb
index 8d4682d890..aec1e79354 100644
--- a/engines/bops_preapps/spec/system/tasks/draw_red_line_boundary_spec.rb
+++ b/engines/bops_preapps/spec/system/tasks/draw_red_line_boundary_spec.rb
@@ -156,6 +156,17 @@
     end
   end
 
+  it "highlights the active task in the sidebar" do
+    within ".bops-sidebar" do
+      click_link "Draw red line boundary"
+    end
+
+    within ".bops-sidebar" do
+      expect(page).to have_css(".bops-sidebar__task--active", text: "Draw red line boundary")
+      expect(page).to have_css("a[aria-current='page']", text: "Draw red line boundary")
+    end
+  end
+
   it "shows correct breadcrumb navigation" do
     within ".bops-sidebar" do
       click_link "Draw red line boundary"
@@ -163,7 +174,7 @@
 
     expect(page).to have_link("Home")
     expect(page).to have_link("Application")
-    expect(page).to have_link("Validation")
+    expect(page).not_to have_link("Validation")
   end
 
   it "hides check red line boundary task when draw task is shown" do
diff --git a/engines/bops_preapps/spec/system/tasks/review_documents_spec.rb b/engines/bops_preapps/spec/system/tasks/review_documents_spec.rb
index 7ff990da6a..e145baab12 100644
--- a/engines/bops_preapps/spec/system/tasks/review_documents_spec.rb
+++ b/engines/bops_preapps/spec/system/tasks/review_documents_spec.rb
@@ -15,6 +15,17 @@
     visit "/planning_applications/#{planning_application.reference}/validation/tasks"
   end
 
+  it "highlights the active task in the sidebar" do
+    within ".bops-sidebar" do
+      click_link "Review documents"
+    end
+
+    within ".bops-sidebar" do
+      expect(page).to have_css(".bops-sidebar__task--active", text: "Review documents")
+      expect(page).to have_css("a[aria-current='page']", text: "Review documents")
+    end
+  end
+
   context "when there are no documents" do
     it "displays a message indicating no active documents" do
       within ".bops-sidebar" do
@@ -36,6 +47,19 @@
       expect(page).to have_content("proposed-floorplan.png")
     end
 
+    it "displays the download all documents button with correct data attributes" do
+      within ".bops-sidebar" do
+        click_link "Review documents"
+      end
+
+      expect(page).to have_link("Download all documents")
+      expect(page).to have_css("[data-controller='download']")
+      expect(page).to have_css("[data-application-reference-value='#{planning_application.reference}']")
+      expect(page).to have_css("[data-download-target='documentsElement']")
+      expect(page).to have_css("[data-document-url-value]")
+      expect(page).to have_css("[data-document-title-value]")
+    end
+
     it "redirects back to the task after editing a document" do
       within ".bops-sidebar" do
         click_link "Review documents"
diff --git a/engines/bops_preapps/spec/system/tasks/summary_of_advice_spec.rb b/engines/bops_preapps/spec/system/tasks/summary_of_advice_spec.rb
index 3596e7851a..43acd384ff 100644
--- a/engines/bops_preapps/spec/system/tasks/summary_of_advice_spec.rb
+++ b/engines/bops_preapps/spec/system/tasks/summary_of_advice_spec.rb
@@ -13,6 +13,17 @@
     visit "/planning_applications/#{planning_application.reference}/assessment/tasks"
   end
 
+  it "highlights the active task in the sidebar" do
+    within ".bops-sidebar" do
+      click_link "Summary of advice"
+    end
+
+    within ".bops-sidebar" do
+      expect(page).to have_css(".bops-sidebar__task--active", text: "Summary of advice")
+      expect(page).to have_css("a[aria-current='page']", text: "Summary of advice")
+    end
+  end
+
   it "Can complete and submit the summary of advice" do
     within ".bops-sidebar" do
       click_link "Summary of advice"
diff --git a/engines/bops_preapps/spec/system/tasks/view_consultee_responses_spec.rb b/engines/bops_preapps/spec/system/tasks/view_consultee_responses_spec.rb
index 8fe7c5c2cf..949e00fbc1 100644
--- a/engines/bops_preapps/spec/system/tasks/view_consultee_responses_spec.rb
+++ b/engines/bops_preapps/spec/system/tasks/view_consultee_responses_spec.rb
@@ -32,7 +32,16 @@
 
       expect(page).to have_link("Home")
       expect(page).to have_link("Application")
-      expect(page).to have_link("Consultation")
+      expect(page).not_to have_link("Consultation")
+    end
+
+    it "highlights the active task in the sidebar" do
+      visit "/preapps/#{planning_application.reference}/consultees/view-consultee-responses"
+
+      within ".bops-sidebar" do
+        expect(page).to have_css(".bops-sidebar__task--active", text: "View consultee responses")
+        expect(page).to have_css("a[aria-current='page']", text: "View consultee responses")
+      end
     end
   end