This week two of the young performers who played Michael - Billy's best friend - fell sick within the course of a few hours and the third actor was 300 miles away in Cumbria.
Only when gale-force winds scuppered plans to transport the third boy to the Victoria Palace Theatre by helicopter did the team cast around for an alternative way to ensure the show went on. And into the breach stepped 13-year-old Liam Mower, who switched from playing his usual role of Billy to take the part of Michael with just one hour's rehearsal.
"I was excited but I was really nervous," he said yesterday. "One of the stage managers told me there was a possibility I might go on for Michael so I jumped into a taxi and they got me to the rehearsal rooms and I rehearsed for a bit. It was all very quick.
"I was waiting to go on and I was really shaking," Liam said. But with six months' experience under his belt, he knew all the lines and the show was greeted with a standing ovation.
Yet the plumber's son from Hull was self-critical yesterday, claiming he had not milked the part for all the laughs it normally got. Neither was he entirely happy with the finale. "I didn't have a clue what to do. They were all pushing me where I needed to be," he said.
But he still loved doing it. "It was the bestest thing I've ever done. It was such an experience. After the show, everyone was saying, 'Oh my God, I can't believe you picked it up so well.'"
Leon Cooke, 14, from Stoke-on-Trent, who played the part of Billy in the tale of a miner's son who chases his dream to dance, might have been rattled by the turn of events having only made his debut in the musical a week earlier.
But he was enormously generous about his co-star with whom he has been friends since they met at the special school set up in Leeds to train children for the musical. "Liam was brilliant," Leon said. "I think it went really well. It wasn't really nerve-racking because we're best mates. Nothing went wrong."
The unscheduled drama began on Monday afternoon when it became apparent that Joey Phillips, who was due to play Michael that evening, could not perform as he had contracted laryngitis. But Ryan Longbottom, the understudy for that performance, was also taken ill with an upset stomach and the doctor ruled that he was unable to perform.
Jessica Ronane, the children's casting director, said: "It was not a situation you anticipate happening at all. It was a complete shock."
They were still hoping to scramble Brad Kavanagh from Whitehaven, Cumbria, when Julian Webber, the associate director, began running through a few scenes with Liam just in case.
"Amazingly, he knew it all backwards. It was really impressive because it means reversing all the choreography, remembering all the moves, all the script," Miss Ronane said.
"I don't think the audience would have known if they hadn't been told. And I think it was good for Liam to go on in a different role. He was fabulous."
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