Queen Elizabeth II dutifully sits through endless hours of displays of military pomp rehearsed to the second -- and secretly loves it when everything goes wrong, Britain's pageant master said on Saturday.
Major Sir Michael Parker, who has spent 46 years producing grand events, told The Daily Telegraph newspaper that the sovereign is most amused when showpiece spectacles descend into calamity.
Parker, 71, has produced more than 320 events including the 80th, 90th and 100th birthday celebrations for the monarch's late mother, queen Elizabeth, plus Victory in Europe and Victory over Japan anniversary celebrations.
Parker recalled the 1977 Silver Jubilee beacon-lighting in Windsor Great Park, west of London, which was his first national spectacular.
He stuffed the beacon full of fireworks as he worried that it might not catch light fast enough.
The Royal Signals major positioned to press the detonator did so prematurely, with the fuse lit by the monarch still fizzing some 60 yards away.
"Can't think why you bothered to ask me!", she laughed.
The sound system was failing and a deafening firework mortar went off instead of a flare.
"The best decision I made in my life was to be honest," said Parker.
"'Your Majesty', I said, 'I'm afraid it's all going terribly wrong.'
Her face lit up. 'Oh good,' she said. 'What fun!'
"I feel sorry for her, having to watch so much dreary stuff all the time. Anything that keeps you awake and makes you smile must be a good thing.
"The Queen is always amused by cock-ups, as long as they’re not serious. Most people would not notice the things that go wrong. She doesn't miss a trick.
"I have always tried to live by my motto: Never tell people what is supposed to happen, then they won't know when it hasn't."
Parker recounted his career in a new book entitled "It's All Going Terribly Wrong: The Accidental Showman".
Now 71, he admitted at 68: "There may be some who think I'm too old for this game... but I only feel about eight. I just love blowing things up."