I am very lucky indeed to have had the privilege of meeing many members of the BRF and/or seeing them in person.
Catherine is indeed tall. I would indeed place her height around 5ft 10in. She is very thin though, and I wonder if that has led some members of the Royal Forums to think that she is petite. By way of comparison, I would estimate that the Princess Royal is around 5ft 5 in - 5ft 6in, but because she is more substantially built - but certainly NOT fat - she could strike people who just have photos to go on as being taller than that.
I have seen Prince Charles, Prince William and Prince Harry playing Polo at the Beaufort. I would estimate that Prince Charles is around 5ft 9 to 5ft 10in. Both William and Harry looked several inches taller than him - I would estimate that both brothers are in the 6ft 2in+ range, which was very clear to see as they were standing alongside their father at the formal prizegiving, all identically dressed in team shirts, white breeches and polo boots.
The Queen is actually quite small - I estimate around 5ft 3in or 5ft 4in at the most. Prince Philip is actually smaller than you would think - even disregarding the fact that most people's spines shrink a bit with age, I would estimate that Prince Philip even at his tallest was around 5ft 9in perhaps 5ft 10in at the most. Because he always carries himself very well, and because he has an air of great authority about him and because the Queen is actually quite small, people often think that Prince Philip is (was) at least 6ft tall.
Princess Margaret and the Queen Mother were both very petite indeed - around 5ft I would estimate.
The Countess of Wessex, The Duchess of Gloucester, The Duchess of Kent and Princess Alexandra are all in the region of 5ft 5in.
Fergie is about 5ft 8in. Because she is both substantially built and rather noisy, the perception is that she is physically taller. I would estimate that Beatrice and Eugenie are around 5ft 6in to 5ft 7in although they were both wearing different heights of high-ish heels when I saw them together, which made it hard to judge even though they were side-to-side. The Duke of York is taller than Prince Charles and I would estimate him as 6ft.
Photographs are often deceptive, particularly official ones. I am absolutely hopeless with the web and the internet, but if someone here can find a picture of the Official Engagement Photo of Diana and Charles and post it here, forum members will notice that Charles looks
several inches taller than Diana
!!
Hope this is of interest,
Alex