No screen heroes this year will trump the bravery of the family at the heart of a British documentary screened at The Times BFI 53rd London Film Festival last night.

Mugabe and The White African, which documents the ordeal of white farmers resisting the land seizures in Zimbabwe, was shot secretly by a British couple, Andrew Thompson and Lucy Bailey, who have previously made short films for Comic Relief.

Their male leads, both of whom travelled to London for the premiere last night, are Michael Campbell, 75, the African of the title, and his son-in-law Ben Freeth.

Mr Campbell’s family have been in southern Africa for 300 years. His fruit farm 70 miles southwest of the capital, Harare, was once the biggest producer of mangoes in the country but for the past four years it has been under siege from armed thugs bent on wresting control.

Mr Freeth, 40, was born in Kent and moved to Zimbabwe when his father got a job there after independence in the early 1980s. He married Mr Campbell’s daughter Laura and they now have three children, aged 4, 7 and 9. So when Mr Campbell decided to stand up to the dictator long after most other white farmers had given up, Mr Freeth was at his side. The film documents their struggle. Much of it was shot under cover against the backdrop of the 2008 presidential election. Mr Mugabe’s opponent, Morgan Tsvangirai, won most votes but pulled out of a run-off after a wave of violence against his supporters. A power-sharing deal was agreed in which Mr Tsvangirai became Prime Minister but Mr Mugabe retained control of most of the real instruments of government as President.

Before 2000 about a third of Zimbabwe’s land was in the hands of 4,400 white farmers while about a million black peasant farmers survived on about the same area. Under Mr Mugabe’s “land reform”, ownership has been substantially transferred from white to black.

All but a handful of the white farmers have given up in the face of intimidation, lawlessness and a spiralling economic crisis.

Mr Freeth and Mr Campbell did not. They took the Government to court, arguing that they were being racially discriminated against and that whites in Zimbabwe had the same right to freedom as any other legally opressed minority.

Mugabe and The White African follows their story from Britain, inside Zimbabwe and in Namibia, where the Southern African Development Community (SADC) tribunal sits.

Days before the case was due to be heard Mr Freeth, Mr Campbell and his wife were viciously beaten after refusing to call it off but eventually the judges ruled that the Government’s attempt to “nationalise” white farmland was illegal and racially discriminatory.

However the historic victory has proved ineffectual inside Zimbabwe. Although the country is part of SADC the Government has ignored the verdict and the campaign against the family has been stepped up.

Mr Freeth said last night: “It is very difficult to exist when you have not got the law on your side. It has been a nightmare for a long time but it has got worse since the unity government [the power-sharing arrangement with Mr Tsvangirai] started.”

He added: “The world needs to step in as they did in 1980 and say, ‘We are going to run this election and let the person that the people want come in and run the country.’ In 1980 the people wanted Mugabe. Now they are tired of him.”

The film will be shown on Channel 4 next year

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010