add question_number method to question

app/helpers/question_view_helper.rb

@@ -5,9 +5,9 @@ module QuestionViewHelper
     { text: caption_text.html_safe, size: "l" }
   end
 
-  def legend(question, page_header, conditional)
+  def legend(question, page_header, conditional, log = nil)
     {
-      text: question.header.html_safe,
+      text: [question.question_number(log), question.header.html_safe].compact.join(" - "),
       size: label_size(page_header, conditional),
       tag: label_tag(page_header, conditional),
     }

app/models/form/question.rb

@@ -258,6 +258,10 @@ class Form::Question
     selected_answer_option_is_derived?(log) || has_inferred_check_answers_value?(log)
   end
 
+  def question_number(log)
+    nil
+  end
+
 private
 
   def selected_answer_option_is_derived?(log)

app/models/form/sales/questions/ownership_scheme.rb

@@ -13,4 +13,8 @@ class Form::Sales::Questions::OwnershipScheme < ::Form::Question
     "2" => { "value" => "Yes - a discounted ownership scheme" },
     "3" => { "value" => "No - this is an outright or other sale" },
   }.freeze
+
+  def question_number(log)
+    "Q3"
+  end
 end

app/models/form/sales/questions/purchaser_code.rb

@@ -8,4 +8,8 @@ class Form::Sales::Questions::PurchaserCode < ::Form::Question
     @type = "text"
     @width = 10
   end
+
+  def question_number(log)
+    "Q2"
+  end
 end

app/models/form/sales/questions/sale_date.rb

@@ -6,4 +6,8 @@ class Form::Sales::Questions::SaleDate < ::Form::Question
     @header = "What is the sale completion date?"
     @type = "date"
   end
+
+  def question_number(log)
+    "Q1"
+  end
 end

app/models/form/sales/questions/shared_ownership_type.rb

@@ -18,4 +18,8 @@ class Form::Sales::Questions::SharedOwnershipType < ::Form::Question
     "31" => { "value" => "Right to Shared Ownership" },
     "30" => { "value" => "Shared Ownership - 2021 model lease" },
   }.freeze
+
+  def question_number(log)
+    "Q4"
+  end
 end

app/views/form/_textarea_question.html.erb

@@ -2,7 +2,7 @@
 
 <%= f.govuk_text_area question.id.to_sym,
   caption: caption(caption_text, page_header, conditional),
-  label: legend(question, page_header, conditional),
+  label: legend(question, page_header, conditional, @log),
   hint: { text: question.hint_text&.html_safe },
   width: question.width || nil,
   **stimulus_html_attributes(question) %>