It must be one of the most eagerly anticipated musicals in recent years. And also one of the most bizarre. When I first heard that Harry Hill was working on a musical based on the X Factor I assumed, like most people, that it was an elaborate joke. After all, wasn't Hill the man who spoofed the talent show monster on TV Burp with The K Factor featuring knitted toys? 

Yet it soon transpired that Hill had come up with the idea, it had reached Simon Cowell and the next thing the public heard was that they were making it together. Cowell's Syco Company has put a substantial figure into the production. And now it is time for the show to prove itself. Nigel Harman plays Simon, comedian Charlie Baker plays a contestant with a hunchback. What more could you want?

I Can't Sing opens at the Palladium later this week. Beyond The Joke spoke to co-writer Steve Brown while the show was previewing. Brown has been a regular musical collaborator with Harry Hill over the years – he was in Harry's Band The Caterers on their last tour.

BTJ: Putting on a  show like this must be a mammoth operation?

SB: It's a bit like hacking away at a giant piece of marble to find the sculpture underneath. On the one hand we wanted to take out the non-laughs, but we also wanted to keep the story. It's all very exciting. The audience don't know what to expect. It's not just a comedy version of The X Factor, it's two very different halves.  This is big. It's a big oil tanker of a thing. 

BTJ: It doesn't sound like your usual West End musical?

SB: Well, we've got a talking dog. Some things have worked out nicely. We already had a Geordie pop singer in it from a band called Loud Girl Noise, who returns to the panel after leaving, and then we heard that Cheryl Cole was returning to X Factor. Harry knows what he is doing. He is a true entertainer and understands the value of song and dance. In a way though it is like a jukebox musical but with new material. But the songs are in all sorts of styles from West Coast rock to hip hop.

BTJ: What about the stories that you were having problems and that's why you had to cancel three previews?

SB: That's what previews are for, to iron out things. All sorts of shows, Matilda for instance, cancel previews for all sorts of reasons. This is a very technical show so we have to get everything right.

BTJ: You've worked in the West End before haven't you? 

SB: I co-wrote Spend Spend Spend so it was odd finding myself as the most experienced person on the team.  

BTJ: What's the best thing about working on I Can't Sing?

SB: All sorts of things. Charlie Baker is great as a rapping Hunchback. He's a real song and dance man. I did suggest to my son Alfie (comedian Alfie Brown) that he could audition for the romantic lead, but he wants to be a comedian. He said 'why would I want to do the same thing every night?'. Also my wife is a very good cook and I've been coming to rehearsals every night so I've missed dinner and lost weight by not eating at home, which is good.

BTJ: And Simon Cowell really does approve even though you are, in a way, sending up everything he believes in? 

SB: He's been to see it. Everyone was watching him, it was quite weird. And afterwards he said 'Fabulous'. 

I Can't Sing opens at the Palladium on March 26. Buy tickets here.