Greg Davies “squealed with joy” when Helena Bonham Carter agreed to appear in The Cleaner

Speaking to RadioTimes.com and other press ahead of the series launch, Davies revealed that he never thought the Oscar-nominated star would agree to take part when he originally sent her the script – but he said he was absolutely delighted when she came on board.

"All I can tell you is that when she said yes, I squealed with joy," he said. "I couldn't believe that... because we sent that script to her written and I didn't for a second think she would say yes."

The episode in which Bonham Carter appears features a healthy amount of toilet humour – including a lengthy scene inside a bathroom – and Davies said that it was this aspect of the script that persuaded her to take on the role.

"I'm sure Helena wouldn't mind me saying that that toilet scene, complete with the surreal nonsense that goes on after, it is what drew her to the project," he revealed. "That's what she was excited by. She's got a healthfully bleak sense of humour, and it was that that made her give it a second read. So yeah, it was great fun. She was great fun!"

And asked which of the guest stars was the most mischievous on set, Davies revealed that one incident involving Bonham Carter was a real highlight – although he remained coy when pressed for details.

"I think all of them brought a different mischief," he said of the cast. "The most remarkable incident was with Helena Bonham Carter, but I simply cannot tell you about it. You can ask her and see if she's happy to tell you about it, but until I have her express permission I wouldn't dare. But suffice to say I laughed a lot!

Inspired by the German series Der Tatortreiniger (Crime Scene Cleaner), the six-part comedy follows Paul ‘Wicky’ Wickstead (Davies) as he dons his hazmat suit and interacts with a revolving cast of characters, “from the victim’s relatives, employers, neighbours and acquaintances, to occasionally even the murderers themselves."

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Speaking about the show previously, Davies revealed, "Each episode is generally a two-hand ‘play’. I mistakenly thought this would be easier than writing for multiple characters. It is not!

"It was nice to just focus on Wicky and the person he encounters each week though. It’s a challenge to make them rounded and to give context to the dreadful events that have led them to be spending time with a crime-scene cleaner."

The cleaner begins on BBC One on Friday 10th September at 9.30pm. If you’re looking for something else to watch, take a look at the rest of our Comedy coverage or check out our TV Guide.