H. P. Grice was born in the heart of England (formerly Staffordshire), so he is English.
G. R. Grice was born in Wales, so he is Welsh.
It may be argued that since 'Grice' is an Anglo-Norman surname or a Scots surname, G. R. Grice is not Welsh-Welsh.
By the same token, Lord Russell, who was born in a part of England that was THEN part of Wales (or viceversa) is both English and Welsh. Call this "Russell's Paradox". Or not!