I don't think it sounds high, cosidering the number of Irish, Polish, Indian and Pakistani nationals - amongst other European, North American, Caribbean and other nationalities - living and working in the UK, contributing to its diversity and broadening culture and knowledge. A large concentration live in and around London, and this has been the case for decades. My partner is from a European countey and would have been one of the non-UK 10% quoted above (for England) had they not gained UK cirizenship years ago (a nightmare of cost and effort, as
@Moth mentioned above), so they're now in the dual-identity 2% figure.
(Edited to use England figures)