Paul Whitehouse says 'Only Fools and Horses: The Musical' is the "most daunting job" he has ever taken on.
The 'Fast Show' star has been waking up in the middle of the night at the thought of playing Grandad in the upcoming musical, which he has co-written with Jim Sullivan, the son of the classic sitcom's late creator John Sullivan, but admits the show is even more "precious" for Jim.
He said: "It's the most daunting job of my career as there is such an affection and love for it.
"I've been waking up at three o'clock in the morning thinking, 'Oh god'. For Jim, it's his dad's, it's very precious, he looks after the archive, he's the caretaker of it."
Paul and Jim have been "very careful" to pen the production with the fans in mind, following the huge success of the TV show, which spanned seven series, 64 episodes and 16 specials, all of which were written by John.
He added to The Sun newspaper: "We developed it very carefully and I'm very conscious of Jim and the family, as well as the fans."
Despite being one of the musical's main stars, alongside Tom Bennett, who will take on the role of Derek 'Del Boy' Trotter and Ryan Hutton, who will star as Rodney Trotter, Paul admits his singing and dancing is "limited".
Speaking on 'Lorraine', he said: "I think I can sing, and if you ask Bob Mortimer he will tell you, 'Will you shut up,' and my children they'll say, 'Shut up, dad,' because I sing all the time.
"I get to sit down for most of it. I thought about that very carefully. I get to sit down for eight shows a week."
Paul insists the show will not be "pretentious", and he and Jim are trying to include as many of the classic comedy moments from the TV series as possible.
He added: "I think sufficient time has elapsed since the end of the series that we can do it without people thinking ... you know, it's a celebration. It's a really fun show. There's nothing pretentious.
"It's a celebration of 'Only Fools' and London and Britain really.
"We're trying to get the chandeliers in but we can't smash antique chandeliers every night."
The show will take place at London's Theatre Royal Haymarket from February 2019 and will include a number of the classic characters from the series, such as Raquel, Denzil, Mickey Pearce, Nags Head landlord Mike, and the dreaded Driscoll Brothers.
Sir David Jason played Del Boy in the original TV show with Nicholas Lyndhurst as Rodney, and Lennard Pearce portrayed Grandad.
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