I'm upholding Sarah Smith's answer and disagreeing with Peter's.
In the natural course of things, the present Duchess of Cambridge will
become queen. It is true that she will be a Queen Consort
rather than a Queen Regnant
, but she will still be a queen.
In fact, the title 'queen' usually describes a Queen Consort, the wife of a reigning king, rather than a reigning queen, if for no other reason than that monarchies are usually male-preference (I know, I know, this is changing in Europe) and historically and through the present, there are a lot more rexes
ruling than reginas
She'll be no more Queen than Prince Philip is King. Most royal "other halves" do not use this title.
No, neither of these statements is true. Most male
royal "other halves" do not use this title because the word 'king' is generally understood to mean a sovereign
. The husband of a ruling queen, therefore, is usually known as a prince consort
, to make it clear that he is not the one reigning. There have been men who have been known as king consort
, but this is unusual.
Are there some inconsistencies in these rules? Yes, absolutely. But as the midwife said to the bishop: I don't make 'em, I just deliver 'em.