Darren McGrady described how he put a dead grouse in a box in the kitchen at Balmoral Castle. When Diana walked in he pulled the string that was attached to the bird prompting her to scream with surprise.
However, the former royal chef added Diana saw the funny side of the joke.
Mr McGrady revealed the prank in a question and answer video on his YouTube channel about working for the Royal Family.
He was asked what the funniest thing that ever happened in the royal kitchen was.
The ex-royal chef said: “We had so much fun over the 11 years I was there with all the other chefs but I remember one time Princess Diana coming into the kitchen at Balmoral.
“I’d put a grouse with all its feathers on, a dead one, into a little string box at the top with some string tied to it.
“All the housemaids were coming in and I was yanking this and they were screaming.
“And then Princess Diana walked in and the head chef at the time looked at me and [shook their head].
“As she got closer I just yanked the string and she screamed but she thought it was funny!”
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“I thought I would be cooking for kings, queens and presidents.
“I did eventually, but one of the first jobs I had was cooking for the corgis, the royal corgis.
“Making fresh food everyday, their own menu.”
Mr McGrady added that the corgis ate chicken, beef, rabbit or liver mixed with rice and cabbage.
He said: “The dogs would have a whole selection of different meats, cabbage and rice.
“The most important part of preparing the meats was that everything had to be cut into a fine dice, something we call a brunoise, a very very tiny cut.
“The reason for that was to be sure that there were no bones at all in the meat.
“Imagine if any of the dogs were to choke on the bones, the chefs would be in real trouble!”