Whoops!
Then of course there is this old chestnut: The No 5 used to have a stiff white dickie as an alternative to the soft "dimple" shirt. Rumour has it that a Regt officer (probably on royal guard duty), was asked to dine with the royal family. The D of E, in full royal dining fig, looked at him wearing his soft shirt and said, "I thought you RAF chaps wore a stiff fronted shirt?" The rattled officer replied, "We do Sir, but only on special occasions!"
D of E's response not recorded!
Ascot