In this article in the Telegraph today, the photograph of the Queen's feet in patent leather shoes gives the impression that either the Queen is wearing shoes that are too small for her (unlikely) or that her feet must have swollen while she has been wearing them. It seems to me that she is experiencing that common problem of having feet that swell as the day goes on because of excess fluid gravitating downward.
The Queen was not overweight when she was younger, but her four pregnancies were probably a big factor in her developing excess fluid retention. I'll bet she's glad to get out of her court shoes at the end of her busy day and put her feet up!
The Queen's problem of fluid retention and swelling feet would be reduced if she were to cut down on salt/sodium and salty food. - If you too, dear Reader, suffer from swollen feet, I make the same suggestion to you. - You will feel sooo much better!