David Oyelowo film to open London Film Festival

Rosamund Pike and David Oyelowo will star in A United Kingdom

A film based on the true story of a Botswana king who married a London office worker will open the BFI London Film Festival.

A United Kingdom stars Rosamund Pike and David Oyelowo.

It tells the true story of the marriage of Seretse Khama, King of Bechuanaland (modern Botswana), and Ruth Williams, a British office worker.

The film, based on the book Colour Bar by Susan Williams, will be shown on 5 October, the festival's opening night.

The couple at the centre of the book faced fierce opposition from their families and the British and South African governments when they married in 1947.

The BBC film is directed by Amma Asante, whose previous credits include Belle.

Clare Stewart, the festival's director, said: "A United Kingdom is testament to a defiant and enduring love story that also reveals a complex, painful chapter in British history."

Assante described her film being chosen as "a great privilege".

The 60th BFI London Film Festival runs from 5-16 October. The festival's full programme will be announced on 1 September.