�In October 2004, the life of 21-year-old trainee chef Essayas Kassahun was tragically cut short in a street fight in Finsbury.

He died in hospital two days after being set upon by a group of youths on the St Luke’s Estate.

A year later and Sam Hallam, from Hoxton, who was 17 at the time of the killing, was handed a life sentence as one of two men found guilty of the murder. Yet Sam, who is now 24, says he wasn’t even there.

He has been battling against the conviction ever since – and now a play has opened that tells his story.

Someone to Blame opens at the King’s Head Theatre in Islington tonight (Tuesday).

Actor Robin Crouch, 21, who plays Sam in his first professional role, said: “I could not play him if I didn’t believe he was innocent.

“As soon as I read the script, I felt angry at what happened to Sam. To play the role, I have to try and exaggerate any injustices I have had in my life by 1,000 per cent.”

The name of the play comes from the words of a key eye-witness, who admitted in court she was looking for “someone to blame” when she accused Sam.

And the script is based entirely on real-life spoken evidence, including transcripts of the trial, police interviews and prison visits with Sam.

Mr Mercatali, 30, whose wife Tess Berry-Hart wrote the script, said: “It was important to meet Sam and know he was happy for his story to be told.

“I was struck by the fact that if Sam is innocent, he wasn’t even there. That must be pretty horrific.

“It’s a tragedy for the victim and his family, but it’s important that Sam’s story is told. If it is a miscarriage of justice, it’s important for society that justice is finally done.”

Sam’s cause has been taken up by the same campaigners who fought for the Birmingham Six.

And last Monday –just a week before the drama opened – they were given hope with the news that an appeal will be heard by the High Court on May 16 and 17. An earlier appeal was dismissed in 2007.

Mr Mercatali said: “When I met Sam, I believed he was innocent. But the play is not part of the campaign. It was important any personal opinion on the part of the writer was taken out of the play, and the audience are allowed to make up their own minds.”

He added: “I’m really hopeful that the appeal will see justice done.”

n Someone to Blame is at the King’s Head Theatre, in Upper Street, N1, until Saturday March 31.