It is true that on the night of Victory in Europe in 1945, 19-year-old Princess Elizabeth (now the reigning monarch) and her 14-year-old sister, Margaret, did go out into public anonymously to join the citywide celebrations in the streets of London. What they actually did once free of palace constraints isn’t known, and so A Royal Night Out is basically House of Windsor fan fiction, though we can presume that the cajoling that Elizabeth (the always wonderful Sarah Gadon: Dracula Untold) and Margaret (a sweetly cheeky Bel Powley) had to do to convince Mom and Dad — aka Queen Elizabeth (Emily Watson: Testament of Youth) and King George (Rupert Everett: Hysteria) — to let them go is probably close to factual. Beyond that, this cute but slight movie gets less convincing even as it remains passably enjoyable as a mildly irreverent caper, one that harkens back to the film comedies of that time. There isn’t much there there; even the class-warfare banter Elizabeth engages in with soldier Jack (Jack Reynor: Transformers: Age of Extinction) is fairly bland, but they have little in common and they have to talk about something when he ends up as her reluctant chaperone for the evening after she loses Margaret and has to find her amidst the wild crowds on the streets she doesn’t know. Director Julian Jarrold’s (Becoming Jane) re-creation of VE night in London is amazing, though, even if it is seen only through the eyes of Elizabeth, who has next to no experience of everyday life for ordinary people and is flustered by coming into such close proximity with it at its most raucous. It keeps a time that must have been terribly exciting at a distance, which is a shame.