Members of the Royal Family are almost always required to appear serious in public as they are often carrying out important duties or meeting people who have suffered from great hardship.
While they manage this effortlessly during their countless official engagements every year, there are a number of opportunities where the chance to showcase their sense of humour arises.
One particularly funny story has been revealed by former Capital Radio presenter and close friend of Diana's, Graham Dene.
Graham, who now hosts a regular show on Boom Radio, has revealed a number of anecdotes to mark what would have been Diana's 61st birthday on July 1.
The enviable story brings together the late Princess of Wales, some of the biggest names in music royalty and, hilariously, Kermit the Frog and Miss Piggy.
Graham revealed: "I’d met Diana quite a few times before when this happened. It was after the Prince’s Trust concert at Wembley in 1988, there was a reception for everybody involved in the Hilton hotel in Kensington.
"Every huge pop star at the time was there - Phil Collins, Peter Gabriel, Joe Cocker, Elton John, Rick Astley, the Bee Gees.
"I arrived, and the event organiser Peter Smith came up to me and pulled me through the hotel, saying, ‘where have you been, she’s been waiting for you, she’s asking for you’. I said ‘who’, and he replied with, ‘the princess!’
"He ushered me into a conference room. He opened the door and there she was - waiting for me! Wow. And she turned to me and said: ‘Graham, I want to tell you a joke.’
"And then she told me this very saucy joke about Miss Piggy and Kermit the Frog. It was a very rude joke and it’s better if I don’t say it - it would make anyone blush! Let’s just say Princess Diana had a very, very cheeky sense of humour.”
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This was not the first time that Diana's love for inappropriate jokes has surfaced. In an extract of royal author Robert Jobson's upcoming book, ‘William At 40: The Making Of A Modern Monarch’, he recounted a story of when Prince Harry started to re-tell one of Diana’s "risqué jokes".
Mr Jobson wrote: “On the school run one morning, she started telling a risqué joke, apparently unconcerned that Harry was drinking in every salacious word.
"Her police protection officer — aware that the language was inappropriate for young ears — tried to stop her mid-flow, but she was having none of it.
“On arrival at Wetherby School in West London, William ran off to his classroom, while Harry immediately started telling the new joke to the headmistress. Belatedly, Diana — who’d gone red with embarrassment — managed to stop him reaching the punchline.”
An excellent story from a royal insider surfaced about the time Sir Donald Gosling told an incredibly crude joke to The Queen about horses and how she reacted when an aide tried to stop her from hearing it.
A courtier recalled: “HM would relish seeing Don because she would know he always had a fresh supply of jokes, but his sense of humour was pretty salty.”
The insider recalled the funny moment during a naval ceremony when Mr Gosling was seated one place away from The Queen, with Labour Defence Secretary Fred Mulley in between them.
“The Minister put up his hand and stopped Don, obviously thinking the Queen shouldn’t be exposed to such ribaldry.
“HM was furious - and berated poor Mulley for ruining the joke. She made Don tell the whole joke all over again, and shrieked with laughter at the punchline, which was about the horse winning against stiff competition, or something like that.”
