It is a well-known fact that Princess Elizabeth ventured out of Buckingham Palace to celebrate among the enormous crowds in London on VE Day in 1945, with the story even serving as the inspiration for the 2015 film, A Royal Night Out.

The princess served in the Auxiliary Territorial Service as a driver and mechanic as a Second Subaltern but was promoted to a Junior Commander after five months of service. The details of the incredible incognito adventure were revealed by the late Queen herself in a rare interview for the BBC in 1985 to mark the 40th anniversary of VE Day.

Looking back, the Queen described that famous evening, saying: "I think it was one of the most memorable nights of my life."

Her Late Majesty went on: "We were terrified of being recognised, so I pulled my uniform cap well down over my eyes. A Grenadier officer among our party of about 16 people said he refused to be seen in the company of another officer improperly dressed, so I had to put my cap on normally.

"I remember lines of unknown people linking arms and walking down Whitehall, all of us just swept along on a tide of happiness and relief. I also remember when someone exchanged hats with a Dutch sailor; the poor man coming along with us in order to get his hat back."

The Queen's first cousin, Margaret Rhodes, was also part of the royal group and remembered that: "Trafalgar Square was jammed. It was a scene of joyful whoopee – full of people kissing policemen and other people."

Margaret added that at 11.30pm the entourage "decided to go in the front door of the Ritz and do the conga. The Ritz was so stuffy and formal – we rather electrified the stuffy individuals inside.

"I don’t think people realised who was among the party – I think they thought it was just a group of drunk young people. I remember old ladies looking faintly shocked. As one congaed through, eyebrows were raised."

While she and her younger sister Princess Margaret had joined King George VI and The Queen Mother on the balcony of Buckingham Palace several times throughout the evening, there was one moment where the Queen recalled standing in front of the palace instead.

She recalled: "We were successful in seeing my parents on the balcony, having cheated slightly by sending a message into the house, to say we were waiting outside."

At 9pm, King George made a broadcast to the nation where he praised the country and everyone who served. He said: "We shall have failed, and the blood of our dearest will have flowed in vain, if the victory which they died to win does not lead to a lasting peace, founded on justice and established in good will."

The King and Queen made an unprecedented eight appearances on the balcony that evening and were even joined by Prime Minister Sir Winston Churchill in a rare, but incredibly fitting, break with tradition.