It sounds like a plot from a mystery playing at a theatre – an actor goes to the toilet only to vanish and never be heard from again.

But in a case of life imitating art, this was the bizarre saga that unfolded at the Gatehouse theatre in Highgate Village.

Leading man Ben Stirling was due to go on stage in the starring role of Jimmy Durante in the theatre’s debut performance of new musical Goodnight Mrs Calabash two weeks ago.

With queues forming outside and just an hour until curtain up, the actor told his fellow cast members he was going to the bathroom.

After 15 minutes they grew alarmed at his absence and went to check him – only to discover he had fled without a word.

John Plews, artistic director of Upstairs at the Gatehouse, said: “We did the dress rehearsal and everybody was happy.

“At around six o’clock some of actors went downstairs to eat, and then the leading man got up from the table and we have never heard from him since.

“At that time we were hoping that maybe he was just sick, but he had done a runner. It was like being left at the altar.”

Mr Plews said it was the first time in his career he had known an actor to “do a Stephen Fry” - a reference to a famous incident 17 years ago when the comedic actor walked out of a West End production before fleeing the country.

“At first we felt sorry for him because he obviously had a problem, but then we felt really angry because he had let down so many people,” the artistic director said.

The unexpected desertion was a major financial blow for the respected fringe theatre, which had to refund 30 tickets bought in advance of the opening night and turn another 30 people away from the door.

And there were some unexpected extra costs.

“The lead role in the musical is Jimmy Durante, a famous American entertainer in the 1940s, who was known as ‘the big schnozzola’ because of his big nose,” explained Mr Plews.

“Ben didn’t have a very big nose so we got a prosthetic nose especially made for him at quite considerable cost.

“Because it was moulded especially to his face, it sadly can’t be used again.”

The theatre has since been told by Mr Stirling’s boyfriend that he has gone to his mother’s in Scotland.

Luckily for theatre goers, a new leading man Tim Frost, who appeared last year in the Gatehouse’s production of Play It Again Sam, has stepped in at short notice so the production can be staged.

“He stepped into the breach and the show will go on,” said Mr Plews.

Goodnight Mrs Calabash will run at The Gatehouse until June 24.