The fire in his dark eyes was raging as Gerry Conlon took me away from the clamour of the post-show party to talk about what he always wanted to talk about – injustice.
Quickly cast aside were the pleasantries about the play which he'd just watched at a Belfast theatre four years ago, and he said: "Why don't you write something about Shaker Ahmed?"
And for the next half-hour one of the world's most famous victims of State wrongdoing told me how he was campaigning for the release of a much lesser known British man locked up in America's Guantanamo Bay.
"His case is just like mine," said Conlon.
"It's a shameful miscarriage of justice too. And anyone who believed in the innocence of the Guildford Four, the Birmingham Six and the Maguire family should sit up and take notice."
His passion disguised the reality that all wasn't well with Conlon, whose story inspired the 1993 Oscar-nominated movie In The Name Of The Father starring Daniel Day-Lewis.
Such was his despair that a psychiatrist who examined Conlon said he was suffering from an irreversible, persistent and disabling post-traumatic stress syndrome.
The real Gerry Conlon came to the surface in the bleaker, quieter moments when he talked, for example, of his cocaine hell and his nightmares.
In one interview he spoke candidly and painfully about his two breakdowns and a suicide attempt.
He also said there were times when he wished he was still in jail.
Paradoxically, he hadn't endured the same anguish during his 15 years locked up for crimes he hadn't committed.
It was only after his highly publicised release in 1989 – when he didn't so much walk as charge like a bull from a London courtroom, an explosive mix of relief and fury – that the problems mounted and he became addicted to drugs and alcohol.
He acknowledged that he was someone who'd been subjected to psychological and physical torture by police after his arrest, and yet still managed to inflict terrifying kinds of torture upon himself after he won his appeal.
At first, despite the inequities of the British justice system, Conlon settled in England, but a request from his ill mother Sarah brought him back to live in Belfast. It was his concern for her in 1975 which led to him signing a false confession to the Guildford bombing after police threatened to have her killed by a soldier on her way to work at the Royal Victoria Hospital in what they said they would claim had been an accidental shooting.
After his release he told the true story of his family's ordeal in a book called Proved Innocent, from which In The Name Of The Father was adapted.
Mrs Conlon did live long enough to hear Tony Blair apologise publicly in 2005 for the wrongful convictions, but she passed away three years later.
"I don't ever want to get a guilty person out of jail," he said.
"But I don't ever want to see innocent people in prison."
His words, said a friend, would be the perfect epitaph for Gerry Conlon.