Actors in period costume chased a thief along a busy high street after he was caught red-handed rifling through bags in the dressing room.
The Woodhouse Players, a theatre group based at the Welsh Church Hall in High Road, Leytonstone, had taken their final bow at the end of 17th century play, Compleat Female Stage Beauty, when the real-life drama began.
The production is set in the 1600s when it first became legal for women to play female roles during the rule of King Charles II.
Dressed as the Duke of Buckingham, James Killeen, 39, of Grosvenor Road in Wanstead, returned to the dressing room to discover a stranger rummaging through bags.
He said: "We didn't recognise the guy. he had cuts on his face and was a bit disorientated.
"He had his hand in a lady's bag. I said to him I'll escort him to the bathroom to clear up his cut but then he just kept walking.
"Something definitely was not right and then he started running."
A "proper pursuit" ensued after a cast member shouted out that her iPhone was missing.
Four cast members, including Mo Wooten from Limehouse, who was dressed as King Charles II, gave chase into Bushwood, joined by audience members and waiters from the Star of India restaurant.
Mr Killeen added: "Those driving along the High Road must have thought they were having a funny turn at the sight of me, King Charles II and Margaret Hughes (the first ever English actress), dashing across the road in hot pursuit of the thief. "
They caught up with the thief near the North Star pub in Browning Road, who eventually handed over the iPhone sent on his way.
Police soon arrived and took statements from the cast members.
Mr Killeen, whose day job is an IT manager, said he was determined not to let the thief get away.
"It was just an instinct and looking back, I'm quite surprised at myself,” he added.
"You put your heart and soul into the performance so we wasn't going to let him get away with it," said the 39 year-old.