Some facts:
Well, if the Cambridges don't turn up to the evening celebrations at BP, it would be an insult to Charles, not the Queen. - But William would never du that to his father, so (as you wrote) pretty sure that they'll be there.
------------------
1. Well, the Queen stopped wearing tiaras during the Royal Variety Performance in the 1980s (the first time was in 1987, although she did wear one in 1989, which was the last time).
2. Despite celebrating her Jubilees in 1977, 2002 and 2012 like no other monarch, she has never (with the exception of her black-tie 60th Birthday Performance at the Royal Opera House in 1986) marked her milestones with tiara-events.
3. But tiaras are still quite common in the British Royal calendar, and is (as you know) still used during the state opening and during white-tie events such as the diplomatic reception and state banquets. - The Queen also used tiaras during all her state/commonwealth visits from 1953 to 2015.
4. And some of Charles' approval-ratings were at about 70% from 2012 to 2017, but went down due to the 20th anniversary of Dianas death.
--------------------
Some of today's front pages:
The Telegraph.
The Times.
The Sun.
The Mail.
