Laura DevlinStephen Daldry added a new dimension to the final interrogation scene in An Inspector Calls, which sees citizens look on in judgment at the central characters. LAURA DEVLIN joined local extras as they rehearsed ahead of last night's curtain up at Norwich Theatre Royal.Laura Devlin

Some of us have had experience of amateur dramatics. Some of us haven't been in a play since school.

But every one of the 12 or so extras waiting nervously in a dressing room had never walked on stage at Norwich Theatre Royal - until last night.

Each time the production moves to a new town or city in its tour of provincial theatres, it gives local people the chance to be part of a crowd scene towards the end of the play. There are no such characters in the J B Priestley text, but, as assistant director Adam Lenson explained, director Stephen Daldry discovered a single word in an older manuscript that made him question who might be onstage with the inspector and the Birlings.

He noticed that the inspector said: 'We are leaving now' rather than 'I', which gave him the idea that a crowd of people could be looking on while he interrogated Eric Birling, the son of the family with a sinister secret. And not just any crowd.

While the play is set in 1912, our eerily silent group is supposed to be a kind of ghostly rendering of 1945, looking back on that hedonistic, pre-first world war era with scorn and resentment.

The central characters are shocked and ashamed by our presence in the wings, but we utter not a word. The acting has to come from eyes, through clouds of dry ice. Meanwhile, 1,300 pairs of eyes will be staring at us from the assembled rows of seats.

Just three hours before the first performance, Adam Lenson gave us a run-through of our stage positions and thanked us for helping out.

We could take a closer look at the amazing set, walk the warren of corridors backstage and feel the excitement building for last night's opener. Then it was just a case of grabbing a quick sarnie, remembering our cues and fighting the urge to cough, sneeze or giggle.

Laura Devlin will appear in today's matinee and will report on her experiences tomorrow.