en-UK or en-GB: the United Kingdom in hreflang
The ISO 3166-1 code for the United Kingdom is
GB. UK is on the exceptionally reserved list:
the code exists so nobody assigns it to another country, but it is not
the country code. Google states that using reserved codes like UK and EU
"doesn't have an effect on Google Search". An annotation with
en-UK is ignored, and the British page loses its regional
targeting without a warning in Search Console.
The fix is a direct replacement of en-UK with
en-GB in every place the cluster declares hreflang: the
HTML head, the HTTP Link header and the sitemap. The same applies to
EU and UN, which have no replacement code. A
page meant for all of Europe uses the language on its own or lists each
country separately.
en-GB in the code reference · en-UK
Check a cluster against every rule in this guide.