Silly question, is the necklace Camila wearing a tiara too?
That's not a silly question at all!
Nine times out of ten if you asked that about a fringe the answer would be that it's a convertible necklace/tiara but this is one of the rare exceptions. According to Hugh Roberts in The Queen's Diamonds, Queen Elizabeth's City of London Fringe Necklace is not convertible to a tiara. A jeweler could modify it so that it could attach to a tiara frame but the BRF haven't needed to do that because they have Queen Mary's Fringe Tiara already.
Here's Queen Elizabeth II double fringing it with Queen Mary's Fringe Tiara and her own City of London Fringe Necklace in 2012 for a diamond jubilee portrait as Queen of New Zealand.
"At seven o’clock on the morning of the wedding, John Dean (Prince Philip’s valet) had tapped on the Duke of Edinburgh’s bedroom door at Kensington Palace where he was staying and entered with his tea. ‘He woke at once and was plainly in great form, extremely cheerful and in no way nervous,’ Dean recalled. ‘There had been a wedding rehearsal the previous day so we all knew exactly what we had to do, and the split-second timings of the day’s arrangements were clear in my mind.’ After Philip had dressed and breakfasted on coffee and toast, the valet gingerly handed him his sword, realising they were ready far too soon. ‘How the Duke resisted the temptation to light a cigarette I do not know,’ Dean recalled. ‘He had given up the habit, as from the previous night, and did not complain.’ "
"From Broadlands, the Princess wrote equally loving letters to her parents. To her mother she said, ‘Darling Mummy, I don’t know where to begin this letter, or what to say, but I know I must write it somehow, as I feel so much about it. First of all, to say thank you … I tried to say the other evening how much I appreciated all you have done for me, but somehow it wouldn’t come. It’s been such fun being together – all four of us – and I hope that we shall have just as much fun, now that you have got a son-in-law!’ She hoped her mother had not been too miserable at the wedding. ‘I was so happy and enjoying myself so much, that I became completely selfish and forgot about your feelings or anyone else’s!’ She thought her mother had looked wonderful: ‘Not just “the bride’s mother” but you – and in the middle of all the fuss and bustle, you were as helpful and wonderful as ever. (I do hope this doesn’t sound sentimental, because it isn’t meant to be – just the truth). I think I’ve got the best mother and father in the world, and I only hope that I can bring up my children in the happy atmosphere of love and fairness which Margaret and I have grown up in. I feel it will be easier for me with such a vivid example and personal experience to guide me!’ The Princess went on to say that she and Prince Philip felt completely at ease together – ‘we behave as though we had belonged to each other for years! Philip is an angel – he is so kind and thoughtful, and living with him and having him around all the time is just perfect.’ "
The Queen Mother - the official biography by William Shawcross