A United Kingdom (2016) offers a divided world an important historical reminder.

Handsomely staged and impeccably acted, “A United Kingdom” revisits and reveals a particularly shameful chapter of Britain’s post-war history and lays bare the callous brutality of 20th Century realpolitik.

The film tells the true story of Prince Seretse Khama (David Oyelowo) of Botswana (then Bechuanaland) who met and married Ruth Williams (Rosamund Pike) an English woman while studying in Britain. Pressing ahead with their marriage against the requests of family and their respective governments they must face the diplomatic weight of the Bechuanaland tribal elders and the British Foreign and Commonwealth Office.

The film wisely concentrates on the relationship between Seretse and Ruth which is brought to life through the fantastic chemistry between Oyelowo and Pike as they take on their friends and family in the name of love. The British Establishment is portrayed with a broad but probably well-deserved mendaciousness, all snooty condescension and moustache-twirling villainy but the real villain of the piece is only ever mentioned, not seen:  the shadowy off-screen presence of the newly segregated apartheid South Africa using their gold and uranium deposits to pressure the impoverished UK government to its will.

Jack Davenport and Tom Felton play perfectly hissible diplomats, whose sense of entitlement and privilege rankle against today’s modern sensibilities and there’s no denying the film has many uncomfortable sequences which bring home some of the realities of colonial Africa. It’s a solid production which, despite its authentic settings, feels more like a particularly star-studded and lavish Sunday evening prestige TV drama than a feature film but that doesn’t diminish the potency of its message.