Her son James (17) was found dead with a gunshot wound to his head at the barracks in Surrey in 2002. He was the last of four young soldiers to die there in similar circumstances.

The play explores the effect on the parents of Private Cheryl James (18), who was found with gunshot wounds in 1995.

Mrs Collinson said she hoped the play would “reignite the flame” of the campaign for a public inquiry into the Deepcut deaths.

“It was like a bolt of lightning — a real emotional roller-coaster,” she said.

“The writers couldn’t have made it better if they’d tried — it was so powerful. I don’t think there was a dry eye in the house.

“If this doesn’t lead to a public inquiry then I don’t know what will.”

Mrs Collinson went backstage to meet the cast of the play and was touched by the support of all the actors and actresses.

“I’ve heard the show is sold-out for its entire run. It’s an excellent piece of work,” she said.

“It was very dramatic and you could see the audience were so appalled at what was portrayed.”