diff --git a/db.json b/db.json
index a04d7101..09def964 100644
--- a/db.json
+++ b/db.json
@@ -1,5 +1,23 @@
 {
   "results": [
+    {
+      "addressLine": "ROYAL MAIL, 20, DONEGALL QUAY, BELFAST, BT1",
+      "subBuildingName": "ROYAL MAIL",
+      "buildingNumber": "20",
+      "street": "DONEGALL QUAY",
+      "town": "BELFAST",
+      "administrativeArea": "BELFAST",
+      "historicCounty": "COUNTY ANTRIM",
+      "ceremonialCounty": "COUNTY ANTRIM",
+      "postcode": "BT1",
+      "country": "NORTHERN IRELAND",
+      "xCoordinate": 146778,
+      "yCoordinate": 530104,
+      "uprn": "185870402",
+      "match": "1",
+      "matchDescription": "EXACT",
+      "language": "EN"
+    },
     {
       "addressLine": "ROYAL MAIL, 20, DONEGALL QUAY, BELFAST, BT1 1FB",
       "subBuildingName": "ROYAL MAIL",
diff --git a/src/config/index.js b/src/config/index.js
index 92d3c764..0583a7ac 100644
--- a/src/config/index.js
+++ b/src/config/index.js
@@ -56,7 +56,7 @@ const config = convict({
   enabledMock: {
     doc: 'Enabled Mock Data for Northern Ireland Names API',
     format: Boolean,
-    default: false
+    default: true
   },
   logLevel: {
     doc: 'Logging level',
diff --git a/src/server/error/index.njk b/src/server/error/index.njk
index 20ab3308..a92de23c 100644
--- a/src/server/error/index.njk
+++ b/src/server/error/index.njk
@@ -6,7 +6,7 @@
 {% block content %}
   {% if statusCode == '500' %}
     {% include 'partials/error-500.njk' %}
-  {% elif statusCode == '404' %}
+  {% elif statusCode == '404' or statusCode == '400' %}
     {% if lang == 'en' %}
       {% include 'partials/error-404-en.njk' %}
     {% elif lang == 'cy' %}
diff --git a/src/server/locations/helpers/get-postcode-type.js b/src/server/locations/helpers/get-postcode-type.js
new file mode 100644
index 00000000..4c53e55d
--- /dev/null
+++ b/src/server/locations/helpers/get-postcode-type.js
@@ -0,0 +1,22 @@
+const fullNorthernIrelandPostcodeRegex = /^BT\d{1,2}\s?\d[A-Z]{2}$/i // Regular expression to match full Northern Ireland postcode format ''
+const partialNorthernIrelandPostcodeRegex = /^BT\d{1,2}$/i // Regular expression to match partial Northern Ireland postcode format ''
+const fullUKPostcodeRegex = /^[A-Z]{1,2}\d[A-Z\d]?\s?\d[A-Z]{2}$/i // Regular expression to match full UK postcode format ''
+const partialUKPostcodeRegex = /^[A-Z]{1,2}\d[A-Z\d]?$/i // Regular expression to match partial UK postcode format ''
+
+function getPostcode(postcode) {
+  let postcodeType = ''
+  if (fullNorthernIrelandPostcodeRegex.test(postcode)) {
+    postcodeType = 'Full Northern Ireland Postcode' // Return postcodeType for full Northern Ireland postcode ''
+  } else if (partialNorthernIrelandPostcodeRegex.test(postcode)) {
+    postcodeType = 'Partial Northern Ireland Postcode' // Return postcodeType for partial Northern Ireland postcode ''
+  } else if (fullUKPostcodeRegex.test(postcode)) {
+    postcodeType = 'Full UK Postcode' // Return postcodeType for full UK postcode ''
+  } else if (partialUKPostcodeRegex.test(postcode)) {
+    postcodeType = 'Partial UK Postcode' // Return postcodeType for partial UK postcode ''
+  } else {
+    postcodeType = 'Invalid Postcode' // Return postcodeType for invalid postcode ''
+  }
+  return { postcodeType }
+}
+
+export { getPostcode }
diff --git a/src/server/locations/helpers/get-search-terms-from-url.js b/src/server/locations/helpers/get-search-terms-from-url.js
index 863d9902..e59fbba4 100644
--- a/src/server/locations/helpers/get-search-terms-from-url.js
+++ b/src/server/locations/helpers/get-search-terms-from-url.js
@@ -1,4 +1,5 @@
 import { LOCATION_TYPE_NI, LOCATION_TYPE_UK } from '~/src/server/data/constants'
+import { getPostcode } from '~/src/server/locations/helpers/get-postcode-type'
 
 const getSearchTermsFromUrl = (url) => {
   let searchTermsLang = ''
@@ -22,23 +23,23 @@ const getSearchTermsFromUrl = (url) => {
   ) // Extract the string between the last forward slash and the interrogation sign
   const parts = extractedString?.split(/[_-]/) // Split by hyphen and underscore
   let searchTerms = parts.join(' ') // Join the parts with spaces
-  // Extract the postcode from the searchTerms variable
-  const postcodeRegex = /\b[A-Z]{1,2}\d{1,2}[A-Z]?\s?\d[A-Z]{2}\b/i // Regular expression to match postcode format
-  const postcodeMatch = searchTerms.match(postcodeRegex) // Match the postcode in the searchTerms
-
-  const isFullNorthernIrelandPostcode =
-    postcodeMatch && /^BT\d{1,2}\s?\d[A-Z]{2}$/i.test(postcodeMatch[0]) // Regular expression to match full Northern Ireland postcode format ''
-  const isPartialNorthernIrelandPostcode =
-    postcodeMatch && /^BT\d{1,2}$/i.test(postcodeMatch[0]) // Regular expression to match partial Northern Ireland postcode format ''
-  if (isFullNorthernIrelandPostcode || isPartialNorthernIrelandPostcode) {
+  const { postcodeType } = getPostcode(searchTerms) // Get the postcode type
+  if (
+    postcodeType === 'Full Northern Ireland Postcode' ||
+    postcodeType === 'Partial Northern Ireland Postcode'
+  ) {
     searchTermsLocationType = LOCATION_TYPE_NI // Set the location type to Northern Ireland ''
-  } else {
+  }
+  if (
+    postcodeType === 'Full UK Postcode' ||
+    postcodeType === 'Partial UK Postcode'
+  ) {
     searchTermsLocationType = LOCATION_TYPE_UK // Set the location type to UK ''
   }
   // Separate the string after the underscore
   const underscoreParts = extractedString?.split('_') // Split the string by underscore
   let secondSearchTerm = '' // Initialize the second search term
-  if (!postcodeMatch) {
+  if (postcodeType === 'Invalid Postcode') {
     searchTerms = underscoreParts[0]?.split('-').join(' ') // Get the part before the underscore // ''
     secondSearchTerm = underscoreParts[1]?.split('-').join(' ') // Get the part after the underscore // ''
   }
diff --git a/src/server/locations/middleware.js b/src/server/locations/middleware.js
index 3e8cdc70..0645841a 100644
--- a/src/server/locations/middleware.js
+++ b/src/server/locations/middleware.js
@@ -47,6 +47,10 @@ const searchMiddleware = async (request, h) => {
   const searchTerms = query?.searchTerms?.toUpperCase()
   const secondSearchTerm = query?.secondSearchTerm?.toUpperCase()
   const searchTermsLocationType = query?.searchTermsLocationType
+  if (searchTerms !== undefined && searchTermsLocationType === '') {
+    request.yar.clear('searchTermsSaved')
+    return h.redirect('error/index').takeover()
+  }
   const redirectError = handleErrorInputAndRedirect(
     request,
     h,