By Laura MacDonald
BBC News, London
When the pub which hosted its plays closed for refurbishment, Theatre 503 decided, quite literally, to get its show on the road.
The play opens as the bus sets off
The south-west London company hired a single-decker bus for its production of Last Tuesday, by Pulitzer Prize winner Donald Margulies.
"Our theatre was closed and we didn't have the money to hire another venue," said the director Paul Higgins.
"Then I remembered that Last Tuesday was set on public transport in America and came up with the idea of staging it on a London bus."
The half-hour production opens as the bus departs from Cleopatra's Needle, on the Thames embankment, taking 30 audience members along for the ride.
"It's a challenge," Mr Higgins admitted.
"There are logistical problems - dealing with four lane traffic and engine noise isn't easy."
Canadian actress Jane Perry, who plays a mother on her way home from work, is thrilled to be part of the production despite its challenges.
"You have to keep focused and not get distracted by what's going on outside the window," she said.
"Performing on a bus is a completely new experience and being so close to the audience is unusual, but I'm really enjoying the change."
Last Tuesday focuses on five ordinary commuters who find themselves having to deal with the threat of terrorism in their everyday lives.
"The play was written post 9/11 but before the London bombings," said Mr Higgins.
"It is not specific to any location but touches on a real issue, showing how we deal with the threat and how resilient we are. It has a positive message."
Nearly five months on from the Tavistock Square bus bomb which killed 13 people, both the play and its unusual venue are sensitive. But Mr Higgins said the audience reaction had been really encouraging.
'Theatre on wheels'
"After the performance, the audience were very eager to talk about what they'd seen.
"The play makes both a political and social statement and because the cast performs amongst the audience, it is very much a shared experience."
Tickets to Last Tuesday, which runs until the 3 December, are free but all donations go to the London Bombings Relief Charitable Fund.
Theatre on wheels seems to be a emerging trend with another south London theatre company, The Battersea Arts Centre, currently staging two shows in the back of a car.