LONDON (Reuters) - Among the jubilant crowds celebrating the end of World War Two, two young princesses mingled and danced incognito on the streets of London.
Slipping out of Buckingham Palace, Elizabeth and Margaret danced a conga in the swanky Ritz hotel, mixed anonymously among the crowds in central Piccadilly and cheered their parents from outside the palace gates at midnight.
Or so tells a new film about Britain's Queen Elizabeth and her late younger sister Margaret and what they might have done on the night of May 8, 1945.
Their cousin Margaret Rhodes has been quoted in British media as saying King George VI and his wife Queen Elizabeth allowed the then 19- and 14-year old princesses to leave the palace, but little is known of how they spent the night.
"A Royal Night Out" imagines just what could have happened.
"It's very much a fantasy ... I think the lightness and the comedic moments of the film really juxtapose the drama and intensity of that moment in time in the post-war era," Sarah Gadon, who plays Princess Elizabeth, said in a promotional interview.
"(There is) a good balance for us to tell this story."
The film stars British actors Rupert Everett as the king, Emily Watson as his wife and Bel Powley as Princess Margaret.
Canadian Gadon, who has previously put on a British accent for "A Dangerous Method" and "Belle", trained with a dialect coach for the film.
"I think when you're going to play such a recognizable figure in the hearts of British people you don't want to mess up the accent," she said.
"If you can't convince people of that then you're lost from the start. So we spent a lot of time focusing on that."
"A Royal Night Out" is released in UK cinemas on May 15.
(Reporting By Reuters Television; Writing by Marie-Louise Gumuchian; editing by Ralph Boulton)