It's the little known story of Queen Elizabeth and her younger sister Princess Margaret - on 8 May 1945, VE Day, the two youngsters, both still princesses, were allowed out of the palace for one night to celebrate. Of course nothing ever goes to plan when teenagers are involved, and a new film, A Royal Night Out, showcases this unlikely story of the future Queen.
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Beginning with Princess Margaret returning to Buckingham Palace the following morning, the trailer takes us back to the previous night, where their father, King George V allows them to join the celebrations - "this might be the only chance she gets."
A mix of humour, drama, and stunning 1940s costumes follow, as this fictionalised account of the true story sees the two abandon their chaperones, proceed to get split up, and see their nights go in two very different directions.
"Chelsea Barracks, Trafulgar Square, Soho..." says Margaret, revealing her destinations for the evening, as older sister, Elizabeth, or Lilibet, meet a handsome stranger, and see a different side of London.
Canadian actress Sarah Gadon takes on the role of Elizabeth while British actor Jack Reynor plays her love interest, a young soldier recently returned from the war.
While Margaret wears a pretty pink dress for her girl's night out, Elizabeth wore her Auxiliary Transport Service uniform, of which she was so proud.
The future Queen regularly kept notes of her activities in diaries, and of her time during the VE Day celebrations, she writes: "Sixteen of us went out in the crowd, cheered parents up on the balcony. Up St J’s (St James’s Street), Piccadilly, great fun."
The next day the pair did it again: "Out in crowd again — Trafalgar Square, Piccadilly, Pall Mall, walked simply miles. Saw parents on balcony at 12.30 am — ate, partied, bed 3am!"
A Royal Night Out is out in cinemas on 15 May 2015