Shaman King has characters that are English and Irish, though the Irish one is not that relevant.
Britain is relevant in all installments of Read or Die/Read or Dream, just don't expect a positive representation. Also Code Geass.
Diana Cavendish from Little Witch Academia is British.
Clow Reed from Cardcaptor Sakura had an English father, I'm not sure it's said where he is born.
I think L from Death Note is English, or at least the orphanage he was raised in is in England.
I'm sure there are tons more of minor characters that are from the UK.>>40854
I suppose every Fate series has at least one character from the UK.