Should Prince Philip be King Philip?
This is the question posed by Birmingham MP John Hemming (Lib Dem Yardley), in a Commons motion calling for an end to "sex discrimination" in the monarchy.
One change to the law is already making its way through Parliament. The Succession to the Crown Bill, which had its first reading in the Commons in December, will end the practice of boys leapfrogging older sisters in the order of succession.
It will mean that the Duke and Duchess of Cambridge's child has the same chance of becoming monarch whether it is a boy or a girl.
But there is another anomaly which won't be addressed.
When the Queen's father George VI became king in 1936, his wife became a queen and was known as Queen Elizabeth (until her husband's death in 1952, after which she was known as Queen Elizabeth The Queen Mother).
MP John Hemming is calling for an end to "sex discrimination" in the monarchy
But the Queen's husband, of course, is Prince Philip, Duke of Edinburgh. Even though she rules in her own right, just as her father did, she cannot make her husband a king.
Mr Hemming has sponsored a Commons motion highlighting this example of "sex discrimination" and calling "for consideration to be given to resolving these constitutional lacunae during the passage of the Succession to the Crown Bill in consultation with those most experienced in dealing with these issues such as HM the Queen, HRH the Prince of Wales and HRH the Duke of Cambridge."