diff --git a/lib/locales/en-GB.yml b/lib/locales/en-GB.yml
index b8aa870dc0..f22499f958 100644
--- a/lib/locales/en-GB.yml
+++ b/lib/locales/en-GB.yml
@@ -86,7 +86,7 @@ en-GB:
       default_country_code:
         - GB
     id_number:
-      valid: '/[A-CEGHJ-NOPR-TW-Z][ACEHJLMOPRSW][0-9]{6}[ABCD]/'
+      valid: '/[A-CEGHJ-NOPR-TW-Z][A-CEGHJ-NOPR-TW-Z][0-9]{6}[ABCD]/'
       invalid: '/(BG|GB|NK|KN|TN|NT|ZZ)[0-9]{6}[E-Z]{1}/'
     internet:
       domain_suffix: