Joker in the pack: How Prince Philip pranked the Royal Family

Watch: Prince Philip's mustard joke used to get him in trouble with the Queen, royals say

The late Prince Philip, who died in April this year, was known for his off-colour and vinegary jokes.

He was famed for his (some say deliberate) gaffes and roars of sudden laughter, and many of his nervous subjects found the Prince's forthright sense of humour slightly alarming.

But to his grandchildren, he was a barbecuing prankster extraordinaire, as a new documentary reveals.

Prince Philip: The Royal Family Remembers features the Queen and Prince Philip's four children, their grandchildren, and members of his long-serving (or perhaps long-suffering) staff, sharing anecdotes and reminiscences of the late Duke.

In it, Prince William recalls that his grandfather's favourite joke at meals was to encourage the children to squirt mustard at the ceiling.

"He used to take the lid off [the tube] and put it in your hands... and then he'd squish your hands together to fire the mustard on to the ceiling," says the Duke of Cambridge. "He used to get in a lot of trouble from my grandmother." Perhaps she had an eye on the cleaning bill.

"He enjoyed those jokes, he enjoyed messing around the children and being a grandfather," adds William, fondly, describing his grandfather as "the heart of the family".

Read more: Prince Charles says his father Prince Philip was ‘marvellous at silly games’ in new documentary

Princess Anne's adult children, now parents themselves, also remember the trick.

"He gets you to hold it in your hands and I can't remember exactly what he says – but he ends up slamming your hands together... it goes all over the ceiling," says Zara Phillips.

"I actually think the marks are still there," says her brother Peter.

Philip's grandchildren also speak admiringly of his relationship with the Queen.

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"The two of them together were just the most adorable couple," says Prince Harry.

“I don’t know if anyone’s ever described them as adorable but, to me, knowing the cheekiness of him and knowing that behind what the world sees, you have two individuals who were very much in love, and both at a very young age dedicated both of their lives to service...

"The places these two travelled, the things they saw, the experiences they went through: that is an incredible bond between two people.”

Harry's comments echo his tribute after Prince Philip's death, when he described his grandfather as “a man of service, honour and great humour... he was my grandpa: master of the barbecue, legend of banter, and cheeky right till the end."

Princess Eugenie adds: "They’re one of the most remarkable couples I think the world has even seen and will ever see. And Granny has been able to be the person she is with the love and support from Grandpa.”

Read more: Prince Philip: Duke of Sussex says his grandfather was 'very much a listener' in memorial show

After his death, Eugenie's touching tribute included her reminiscences: "I remember laughing at your jokes, and asking about your spectacular life and service in the navy," she wrote on Instagram.

The family also praise his barbecuing skills – Eugenie has spoken in the past of his 'swooping in' to rescue her burned sausages, and Prince William has said:

“My grandfather makes my grandmother laugh.

"One of the things I know they’ve loved over the years is when things go wrong, they absolutely adore it... They’re the first to laugh.”

In fact, both loved practical jokes, according to reports. Once, during their tour of Canada in 1951, the Duke of Edinburgh "chased Her Majesty down a train corridor wearing a set of giant false teeth".

It makes a spot of mustard on the ceiling look quite mild.

Prince Philip: The Royal Family Remembers airs on BBC One on Wednesday 22 September.

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