Harry Hill has admitted feeling nervous about staging part of his X Factor musical at the Royal Variety Performance.
The TV star showcased performances from the stage show, I Can't Sing!, at tonight's (November 25) star-studded event at the London Palladium.
He said: "I am a little bit nervous. You kind of feel for them (the cast) because the show hasn't been in rehearsal yet... But that's showbusiness."
The X Factor has been hit by a slide in viewing figures, and TV Burp star Harry said that this would be reflected in the musical.
"There is a gag. We had to cut it out from this (the Royal Variety Performance) because we haven't got time. Max (a ukulele enthusiast) says 'You must have heard of The X Factor. Last season's viewing figures peaked at 20 million'. Then the phone rings with 'eight million viewers'."
Harry said that he was nervous about including a reference to Cowell becoming a father, but added: "The baby will be out at the time of the musical."
Asked if there would be a baby character on stage, he said: "We're reacting all the time. We can add new jokes every day as Simon's life is like a soap opera."
He added: "We have got a reference to Simon's ability to get women pregnant... by looking at them."
Harry said that the musical would not "go for the jugular" and would appeal to fans of The X Factor, as well as people who do not like the ITV talent show.
He said: "Simon Cowell's been great - he's been in America so he's left us alone pretty much. I'm a pretty good judge on how far you can go with this stuff."
He said the Spice Girls' musical flop had not put him off.
"I don't consider fear. If you lived life like that, showbusiness would be the wrong business to be in. It's a very different show to that (the Spice Girls' musical).
"Of all the things I have done... this musical is something I'm really confident about."
Harry said that he had no celebrity cameos planned, but would consider them further down the line.
The Royal Variety Performance will be screened on ITV on Monday December 9.