Stunned theatregoers were all asked to leave Manchester Opera House after a medical emergency involving cast of the new musical I Should Be So Lucky. Audience members had taken their seats at the Opera House on Sunday afternoon waiting for the musical to start, when an announcement was made saying the show was off.

The show has been staging its world premiere run in Manchester, and has been playing to rave reviews since the start of November. It features the chart-topping 80s and 90s hits of super producers Stock Aitken and Waterman and even features a guest role by Kylie Minogue herself in a magic mirror.

But at Sunday's matinee performance, the stunned audience were informed that a cast member had been hospitalised minutes before the show was due to begin. They say they were also told other members of the cast were unwell so they could not stage the show.

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The audience were left to file out of the Opera House and were handed printed forms by staff on the way out onto Quay Street. The forms explained how refunds would be processed following the shock announcement.

Theatre-goers have told how they were waiting for half an hour in the theatre expecting the show to start before the announcement was made. Many simply thought the show was running late.

The Manchester Opera House and producers of I Should Be So Lucky have apologised for the disruption. In a statement to the MEN today they said: “We’re hugely sorry that the Sunday matinee performance of I Should Be So Lucky had to be cancelled due to sudden company illness, with one member of the cast being admitted to hospital close to the start of the show.

"It is never taken lightly to cancel any performance and all involved are very sad it could not go ahead. As the show is so new, covers are still being rehearsed, meaning it was not possible for this performance to go ahead without this cast member."

Audience member Nicky Lewis, 45, from Wigan attended with husband Michael and was annoyed that the audience were left in the dark for so long. She said: "Everyone was buying snacks and drinks, souvenirs and programmes and then we went into the auditorium and were sat there until 3pm, when it should've started at 2:30pm.

"An announcement was finally made that a cast member was in hospital and that four more of the cast were ill and they said the performance couldn't go ahead.

"Surely they would've known all this before most of us arrived at the theatre yet they allowed everyone to go and get more drinks. You've allowed people to spend money on drinks, but then they had to down them and leave."

Nicky added that the couple had booked an overnight stay in Manchester especially to watch the show, but when it was cancelled instead were left heading to the Christmas Markets in the rain.

Audience member Olivia Malone and her boyfriend also ended up at the Christmas Markets after the show was cancelled. She said: "We took our seats at about 2.15pm so were sat in the theatre for about 45 minutes in total before an announcement was made at 3pm.

"They said something along the lines of due to cast member hospitalisation today's performance has been cancelled and as the show is new the supporting cast are not fully trained."

Theatre bosses say that all performances of I Should Be So Lucky are due to resume for the rest of the week. The show will play in Manchester from Tuesday until Saturday November 25, before embarking on a UK tour.

Their statement added: "All performances this week in Manchester are set to go ahead. For those who were due to see the cancelled performance, ATG Tickets will be in contact over the coming days to confirm the options available regarding exchanges or refunds, please visit your place of purchase for further information and we hope you can come back to see us.

"We apologise again for this cancellation."