A Royal Night Out, film review: Sarah Gadon earns her crown as a princess out to party

(12A) Julian Jarrold, 97 mins. Starring: Sarah Gadon, Bel Powley, Jack Reynor, Rupert Everett, Emily Watson

Bel Powley and Sarah Gadon in ‘A Royal Night Out’

It is VE Day and the two young princesses Elizabeth (Sarah Gadon) and Margaret (Bel Powley) are "completely cheesed" at being locked away in a "ghastly mausoleum" (that is to say, Buckingham Palace) when the rest of Britain is celebrating. They somehow persuade daddy and mummy (a stuttering Rupert Everett as George VI about to give his king's speech and a clucking Emily Watson as Queen Elizabeth) to allow them out to celebrate "incognito" with the rest of the London crowds.

Jarrold's film takes a slither of an anecdote (apparently, the princesses really did join the VE Day festivities) and builds a Smiles of a Summer Night-like comedy around it. Elizabeth (an improbably beautiful Gadon, speaking in a Celia Johnson-like voice) and Margaret (Powley in fine comic form) quickly wriggle free from their chaperones, become separated from each other and have a turbulent night. Their travels take them from nightclubs to knocking shops, from the fountains of Trafalgar Square to Chelsea Barracks. Their drinks are spiked. They encounter spivs (among them the splendid Roger Allam), bus drivers, prostitutes, nightclub heavies and plenty of leering officers who try to spike their drinks with "bennies".

Sisterly love: Sarah Gadon (left) as Princess Elizabeth with Bel Powley's Princess Margaret

Much of the film is concerned with Elizabeth's blossoming relationship with the working-class airman Jack (Jack Reynor) who has gone AWOL and will be arrested if the Military Police get near him. He is staunchly republican and doesn't think much of pampered princesses in high-heeled shoes.

It is here that A Royal Night Out becomes skewered on the horns of a dilemma from which it can never quite wriggle free. On the one hand, it is trying to be a romantic comedy. On the other, the screenwriters realise the very suggestion that the young Elizabeth might have had a fling with an airman verges on the treasonous. The film begins to pull its punches and to become ever more improbable.

Even so, this is a poignant and entertaining affair, with enough of a satirical edge not just to seem like an exercise in cosy British nostalgia. Gadon is exceptional as the cocooned young princess who adjusts with surprising pragmatism to life beyond the palace gates.