THE ex-boyfriend of Lady Gabriella Windsor claims they swam naked in the Queen's swimming pool and took MDMA at Windsor Castle.

In a scathing tell-all article about the Royal Family journalist Aatish Taseer - who dated the daughter of the Queen's first cousin for three years - also likened the royals to the Nazis.

In his Vanity Fair article the 38-year-old claims the "royals and Nazis go together like blini and caviar".

He also claims his girlfriend's mum - Princess Michael of Kent - owned two black sheep called Venus and Serena after the top African-American tennis sisters.

A member of the Queen's press office declined to comment.

In the explosive article he wrote: "For three surreal years, Ella and I hung about Kensington Palace; we swam naked in the Queen's pool in Buckingham Palace; we did MDMA in Windsor Castle; and we had scrapes with the British press."

Continuing his critique the writer dubbed his stay at Kensington Palace "wildly depressing" likening the exterior to a mix of "a military hospital and an old people's home."

He continued: "All the famous inhabitants - Princess Margaret and Princess Diana - were dead, and those who remained, minor royals and palace secretaries, lived in their long cold shadow."

"I do have happy memories of KP – Burmese cats in window seats and wooden commodes, deep bathtubs and walled gardens – but the truth is until Will and Kate arrived to liven up the place, Kensington Palace was wildly depressing."

London-born Taseer is the son of a Indian journalist Tavleen Singh. His dad Salmaan Taseer was a politician who was assassinated in 2011.

The pair met the US in 2003 through mutual friends and soon begun dating.

Taseer - who earned the nickname 'Captain Condom' after a sexual health day fancy dress outfit - was even tipped to marry the royal 50th in line for the throne.

The couple ended the relationship in 2006.

However Taseer alleges Princess Michael was convinced it was a bad idea for the royals to tie the knot with commoners.

He wrote: "She once said to me 'It's all very well Ella marrying Mr Taseer from India or Pakistan. No one knows what to do with that. But the moment the girl down the road thinks she can be Princess, or Queen, it's all over. The mystery is gone."

The Princess Michael of Kent sparked fury last year for wearing a "racist" blackamoor brooch when she was first introduced to Meghan Markle.

A spokesman told The Sun Online at the time the brooch was a gift that the royal has worn many times before.

The spokesperson continued: "Princess Michael is very sorry and distressed that it has caused offence."