Prince William was left embarrassed when his mother Princess Diana surprised him with a very unconventional birthday cake for his 13th birthday.

The Prince of Wales is celebrating his 42nd birthday today and his family are no doubt making a fuss of him at their home Adelaide Cottage in Windsor, with the usual thoughtful touches such as a gift, perhaps some celebrations and a birthday cake to enjoy together.

But no doubt this year William will be enjoying a rather more tasteful sweet treat than his 13th birthday cake, which former Buckingham Palace chef Darren McGrady revealed was ordered by Diana  to be delivered to Kensington Palace.

Chef Darren McGrady previously told The Daily Mail: ‘I found it in the fridge. It was in the shape of a huge pair of boobs with equally huge nipples.

‘I was astonished and went through to the butler and asked who’d ordered it. He told me it was the princess and it was a surprise for William.

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Princess Diana (left in 1995) famously loved to play pranks on sons Prince Harry (centre) and Prince William (left)

‘At the time the prince had a super-crush on the models Christy Turlington and Claudia Schiffer.

‘The princess’s hairdresser Sam McKnight knew them and he got them to come to the palace for his birthday tea – and that cake, of course. William was bright red all afternoon.’

The late Princess of Wales was known for her cheeky sense of humour and couldn’t resist that chance to embarrass her eldest son on his milestone birthday.

Prince William may have been left red-faced by the incident, but his brother Prince Harry – who was just 10 at the time – found the prank hilarious, sharing his mother’s cheeky sense of humour.

Prince Harry liked the prank so much that he reportedly asked for the same cake for his own 13th birthday.

While Princess Diana might have organised William’s elaborate birthday cake, the chances of her attempting to bake one herself would have been very slim, with McGrady revealing that she was a ‘terrible cook’.

‘She couldn’t cook, the Princess was a terrible cook, she really was,’ he told HELLO! ‘I would actually leave food for her.

‘I worked Monday to Friday and I’d leave food in the refrigerator for the weekend, like stuffed peppers, she loved those for a weekend lunch.

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Prince William’s 21st cake, given to him on Thursday June 19, 2003, during a visit to the Anglesey Food Fair in north Wales, was much less risque

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Princess Diana (centre in 1995) shared a close bond with her sons Prince William (left) and Prince Harry (right)

‘I actually put cling film on with a little sticky note with a number two on it, and that told her to put it in the microwave and press two. That’s just how bad she was at cooking!

For William’s 13th birthday, exactly 29 years ago, his mother didn’t stop at a saucy cake.

Knowing her son had a crush on iconic ’90s supermodels like Claudia Schiffer, Christy Turlington and Naomi Campbell, his mother invited them over to wish William a happy birthday – and the flustered teenager ‘pretty much fell down the stairs in response’.

‘I was probably a 12 or 13-year-old boy who had posters of them on his wall. And I went bright red and didn’t know what to say and sort of fumbled and I think I pretty much fell down the stairs on the way up,’ The Mirror reports William revealed in a 2018 documentary.

‘I was completely and utterly sort of awestruck. But that was a very funny memory. That sort of childish, fun element really came out when she [Diana] was spending time with us.’

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Prince William will likely be celebrating his 42nd birthday with his wife, the Princess of Wales, and their three children, Prince George, Prince Louis and Princess Charlotte. Pictured at Trooping the Colour 2024

Prince William went on to say how his mother ‘was a total kid through and through’.

He continued: ‘All I can hear is her laugh in my head. That sort of crazy laugh of where there was just pure happiness shown on her face.’

Tributes have been pouring in for Prince William on his 42nd birthday, with the King leading the messages with a sweet throwback snap on social media.

The caption, which sits alongside a archive photo of Prince William as a baby with his father Charles, reads: ‘Wishing the Prince of Wales a very happy birthday!’