Not to be pedantic, but if Nayef is Welsh, then like his wife, he is also "British." British refers to the whole island of Britain and as a citizenship includes Northern Ireland. Great Britain means the whole British island which is divided into three countries, Wales, Scotland and England - perhaps you meant that Nayef's wife was English or Scottish since in any case both Scots and English as well as the Welsh are all British.
That said, each of the four countries, England, Scotland, Wales and Northern Ireland (Ulster) speak English as an official communal language, however, Wales, Scotland and Northern Ireland each have their own individual language, all three languages having a common root that is Celtic. They are NOT dialects of English, they are independent languages that predate English by thousands of years.
Thank you for taking the time to read this, this is to demonstrate at least the Welsh language.
(Below is the same sentence in Welsh.)
Diolch am gymryd yr amser i ddarllen hwn, mae hyn er mwyn dangos y Gymraeg o leiaf.