Surprisingly, there is no law declaring English the official language of the UK.
In fact, English is just the de facto official language of the UK, which means it is not legally sanctioned as official but spoken by the majority.
England and Scotland do not have any official languages. Northern Ireland’s official languages are English and Irish.
Welsh and English are the official languages of Wales
“The Welsh Language (Wales) Measure 2011 recognises that Welsh and English are official languages” - https://en.m.wikipedia.org/wiki/Welsh_Language_(Wales)_Measure_2011
The linked article
and your Wikipedia link bothstates that only Welsh is recognised by Wales as an official language.Edit. Apologies, your quote is further down. It’s appears I’m wrong, and Wales do recognise English.