Ordeal by Innocence: how Ed Westwick was replaced in BBC's Agatha Christie drama

When Ordeal by Innocence was dropped from the BBC Christmas schedules, Agatha Christie fans feared it would never see the light of day.

Ed Westwick, a key member of the ensemble cast, was accused in November of historic allegations of sexual assault, which he denies.

But as the drama finally airs on BBC One on Easter Sunday, the programme-makers have revealed the extraordinary lengths to which they went in order to salvage the production,  including re-shooting 35 scenes - at a cost of up to £2 million - that replaced Westwick with another actor, Christian Cooke.

Over 12 days in January, the cast were recalled to the Ardgowan estate near Inverclyde, Scotland, which had to be re-dressed with props and decor to recreate a country house from the 1950s.

Costumes had to be flown back from Paris and Rome, where they were being used in other productions. Cooke was given several weeks to learn his lines.

Filming in the depths of winter presented a significant challenge, as the murder mystery is set during a balmy summer. Eagle-eyed viewers may spot one scene in which Cooke is outside on a ‘summer’ day, but his icy breath is visible in the air.

The re-shoot had the blessing of Christie’s estate, which is run by the author’s great-grandson, James Prichard. He said: “A lot of work had gone in, a lot of people had spent a lot of time on it, and we didn’t want to lose it. It’s as simple as that.

“What seemed an impossible idea - that you may be able to get a bunch of actors back, however much later, and that you can film July in January in Scotland - was actually achievable.”

The producers took their inspiration from All The Money In The World, Sir Ridley Scott’s film about the 1973 Getty kidnapping, which was re-shot with Christopher Plummer when Kevin Spacey was dropped over allegations of sexual impropriety.

The plot is a whodunnit involving the family of Leo and Rachel Argyll, played by Bill Nighy and Anna Chancellor. When Rachel is murdered, her five adopted children are among the suspects. Westwick played one of the children, Mickey Argyll.

Anthony Boyle, who played Westwick’s brother, was in New York rehearsing for the Broadway opening of Harry Potter and the Cursed Child when he was called back for the reshoots. Another actor, Matthew Goode, was able to fit his scenes into a 12-hour window between other projects.

Sandra Goldbacher, the director, said: “We could restage a lot of the scenes completely rather than do it piecemeal.”

But there was one glitch. Alice Eve, cast as Nighy's new wife, was prevented from flying in from the US at the 11th hour by visa problems.

As a result, she does not appear ‘live’ in any scenes with Cooke. Instead, Cooke filmed them separately then was merged into shot using split screen technology.

“We live in a world where we have the most extraordinary wizards and technical expertise,” said Sarah Phelps, the screenwriter. “Who knows if it’s just going to be All The Money In The World and Ordeal by Innocence who have to do this, or if it will happen more often.”

The actors were remunerated for their time. Asked if she had received a bonus, Chancellor joked: “We got paid. Do you call being paid a bonus?”