Channel 4 is to broadcast a “revisionist” documentary on Lord Snowdon and Princess Margaret's marriage next month.

Snowdon and Margaret: Inside a Royal Marriage, produced by Wildcard Productions, tracks the 18-year marriage through the eyes of friends and family, many of whom speak on TV for the first time.

The film will feature a mixture of archive, interviews and reconstructions and was commissioned to capitalise on interest in Lord Snowdon's hedonistic life following next week's publication of his official biography.

The doc will be produced and written by Leoni Jameson, who previously made The Queen's Story for ITV to mark the golden jubilee. It will be executive produced by Narinder Minhas.

“It's a revisionist take on a well-known relationship,” said Jameson. “We've worked closely with his biography and have secured incredible access to the people around him.”

C4 specialist factual commissioning executive Liz Hartford ordered the 60-minute documentary, which will air at 9pm on 25 June.