Set back from the street, down dingy courts or in the recesses of a grubby alleyway, the stage door is often out of the way and hidden from public view. It separates the hurly burly off-stage reality outside a theatre or opera house, from the drama behind the curtain and out front on stage. Why does it remain, for most of us, a curious and peculiar place?

In Stage Door, actress Rachael Stirling reveals its secrets, unwritten rules and routines - and we get a glimpse of what happens in the moments before and after crossing the threshold, past and present. However unglamorous its environs, visitors become momentarily enchanted, whether for a fleeting glimpse of John Gielgud or Peter O'Toole, an autograph and a smile from Margot Fonteyn, or the shock of seeing Simon Callow in his pants.

Staking out the stage door, we hear from 'stage dooring' fans and autograph hunters as well as actors, cast members and crew. In the middle is the stage door keeper, determining who goes in and what stays out, organising its transitory residents and protecting the performers when the show comes in. "One time in Newcastle, Ray - smashing fella - picked up a bad vibe from someone waiting for me" explains Shaun Williamson. "The guy was waiting to assault me for something that Barry Evans had done on screen in EastEnders."

Contributors: Shaun Williamson (Barry from EastEnders); Harry Gabriel, stage door keeper at London's Shaftesbury Theatre; house assistants Tom Shallaker and Martha Lamb from The Lyceum and Crucible in Sheffield; opera critic Rupert Christiansen; actor Geoffrey Streatfield; and Geoffrey Marsh, Director of Theatre Collections at The Victoria and Albert Museum.

Producer: Tamsin Hughes

A Testbed production for BBC Radio 4.