diff --git a/doc/default/id_number.md b/doc/default/id_number.md
index 89216c0279..b53bfe52ff 100644
--- a/doc/default/id_number.md
+++ b/doc/default/id_number.md
@@ -50,3 +50,24 @@ Faker::IdNumber.danish_id_number(gender: :female) #=> "050390-9980"
 # Generate a valid French Social Security number (INSEE number)
 Faker::IdNumber.french_insee_number #=> "22510589696868"
 ```
+
+## ID Number and Locales
+
+Besides the default ID numbers, faker supports localized `.valid` and `.invalid` values:
+
+```ruby
+Faker::Config.locale = 'fr-FR'
+Faker::IdNumber.valid #=> "22510589696868"
+```
+
+Locales with specific intricacies are as such:
+
+### en-GB
+
+When the locale is set to British English, unformatted [National Insurance](https://www.gov.uk/national-insurance/your-national-insurance-number) numbers are generated:
+
+```ruby
+Faker::Config.locale = 'en-GB'
+Faker::IdNumber.valid #=> "AJ405924A"
+Faker::IdNumber.invalid #=> "BG316764W"
+
diff --git a/lib/locales/en-GB.yml b/lib/locales/en-GB.yml
index 0a50f78714..b8aa870dc0 100644
--- a/lib/locales/en-GB.yml
+++ b/lib/locales/en-GB.yml
@@ -85,6 +85,9 @@ en-GB:
         - Northern Ireland
       default_country_code:
         - GB
+    id_number:
+      valid: '/[A-CEGHJ-NOPR-TW-Z][ACEHJLMOPRSW][0-9]{6}[ABCD]/'
+      invalid: '/(BG|GB|NK|KN|TN|NT|ZZ)[0-9]{6}[E-Z]{1}/'
     internet:
       domain_suffix:
         - co.uk
diff --git a/test/test_en_gb_locale.rb b/test/test_en_gb_locale.rb
index d12cf30cb9..8a921b0c86 100644
--- a/test/test_en_gb_locale.rb
+++ b/test/test_en_gb_locale.rb
@@ -69,4 +69,18 @@ def test_en_gb_postcode_outcode_is_valid
     assert_match(/^[A-PR-UWYZ][A-HK-Y0-9]/, outcode)
     assert_match(/\w{1,2}\d{1,2}|\w\d[ABCDEFGHJKPSTUW]|\w\w\d[ABEHMNPRVWXY]/, outcode)
   end
+
+  def test_en_gb_id_number_valid
+    id_code = Faker::IdNumber.valid
+
+    assert_equal(9, id_code.length)
+    assert_match(/^[A-CEGHJ-PR-TW-Z][A-CEGHJ-NPR-TW-Z][0-9]{6}[A-DFM]$/, id_code)
+  end
+
+  def test_en_gb_id_number_invalid
+    id_code = Faker::IdNumber.invalid
+
+    assert_equal(9, id_code.length)
+    assert_not_match(/^[A-CEGHJ-PR-TW-Z][A-CEGHJ-NPR-TW-Z][0-9]{6}[A-DFM]$/, id_code)
+  end
 end