(This is not the same as her mother being Queen Elizabeth I, which was the tudor queen from the 1500s, wife-of-king queens don't take up a number).
It's a weird bit of asymmetry to the husband-of-queen title being decided on an adhoc basis, having been a prince of denmark, prince-consort of the united kingdom and prince of the united kingdom respectively.
The asymmetry derives from an asymmetry in the titles themselves: the title "King" outranks the title "Queen", rather than those titles being of equal rank. You can't have someone other than the monarch outranking the monarch, so the husband of the reigning Queen can't be a King.