Following on from the Ryan Giggs and the other non English players in the men's and ladies teams not singing God Save The Queen.
Personally I think it's inevitable that these players migjt not want to or feel odd singing it due to the fact that team GB doesn't exist out side of the Olympics and a) these players will always be used to singing their own Athems before matches, b) God Save etc is Englands anthem too so is always sung by the "opposition" in any home international v England.
If England had their own anthem like the scots and the welsh and GB had its own anthem it wouldn't be a problem.