During the press conference that followed, Mr Nicholls' smiling demeanour faltered just for a second when he mentioned Mr Hill's name during a long list of "thank you" dedications, and he momentarily broke down with emotion. It was a measure of the closeness that has developed between the two men, even though they did not meet for many years.
Earlier in the day, while waiting for the court's decision, Mr Hill, who was acquitted after serving 16 years for the IRA pub bombings in Birmingham, told of the secret network of innocent prisoners within the system. While they were often in separate prisons, these men would keep in constant touch to offer each other moral support and advice as to how they should continue their battles for justice.
In fact, the first time Mr Hill actually met his friend was after his own release in 1991 when he started to visit him in jail. But by then they had been in close contact for 13 years. The nearest they had previously come to meeting was when Mr Nicholls had arrived at Parkhurst on the Isle of Wight in 1978, just as Mr Hill was leaving.
"Prisons were small places for people like us. There were only eight or nine prisons they would house us in," said Mr Hill, a slight, greying 53-year-old. "Between the prisons, you find out on the grapevine who is innocent and who isn't. People who protest their innocence get moved around a lot, it seemed, because we were always bucking the system and not conforming."
They would keep in touch, he said, using this grapevine and through what they call "dead letters" - notes sent outside the prison postal system, which is still subject to censorship for category A prisoners.
"You could communicate by word of mouth and you could give letters to people who were in transit. We had this network set up all over the country," said Mr Hill. The Guildford Four, the Bridgewater Four, the Cardiff Three and the Tottenham Three were all part of the system.
Cynics might say that everyone in prison would claim to be innocent. But Mr Hill explained that it was not hard to sort out the genuine cases from those who were trying it on.
"You get a lot of guilty men who pretend they are innocent and it's all a ploy, but after a while they just give up and admit the truth," he said. "You found out who was fitted up. With Paddy, he never stopped fighting. That man could have had parole 10 years ago if he'd just said he was guilty."
Mr Hill said that he had been fighting for Paddy Nicholls' acquittal ever since he was himself released, and visited him every six weeks. While still inside, both had also helped with other prisoners' cases by writing letters on their behalf. "Paddy used to help other people who didn't understand all the technicalities. I used to help people as well with writing and other things."
He described how he picked his friend up from Albany Prison on the Isle of Wight on a freezing, rainy day last February. Mr Nicholls was wearing an old pair of trousers, a T-shirt and a thin windcheater jacket. "I thought he was going to die in my arms. That man had a stroke at Christmas. He was on 20-30 tablets a day but they threw him out of prison without medication," said Mr Hill.
They now live together in Paddy Hill's flat in north London, a condition which had been set by the courts. Mr Nicholls' family deserted him years ago. "He hasn't adjusted. You don't adjust," said Mr Hill. "He can't afford to get angry about what has happened because of his health. The next thing could take his life away." His friend will, however, be pursuing his claim for compensation through the European courts, on the grounds that the Home Office "hasn't got a clue".
Despite today's victory, it seems on recent experience that Mr Nicholls will have little opportunity for traditional forms of celebration. He cannot drink, maybe occasionally visiting the pub to sip a half-pint of Guinness, and his general state of health remains extremely poor - "he's semi-paralysed", says Mr Hill. Mostly, Mr Nicholls spends his time at the computer, writing his memoirs.
For Mr Hill, too, his work for those he believes to be wrongly imprisoned goes on. "There are thousands of innocent people in jail, I just campaigned for him like many others," he said.
The problem for those who are innocent, say prison staff, is that they are likely to end up having a harder time inside than those who admit their guilt and settle down to do their time. Governors stress that all inmates are dealt with the same, and that it is the duty of the Prison Service to uphold the decision of the courts until such time as it may be changed. But prison officers say that people who believe they have a genuine grievance are more likely to end up in trouble within the system through mounting protests, and so suffer segregation and other punishments. Also, like Paddy Nicholls, they can find themselves serving extra time because of a refusal to admit guilt.
"It's like a Catch 22," said Mark Freeman, assistant general secretary of the Prison Officers' Association. "There is a culture in the system that says that someone's release should be put back unless they address their crime, and attend classes and therapy sessions. In general, this is a very important part of protecting the public, but for an innocent man it is very difficult. Either he sells out and admits his guilt, even though he knows he is not guilty, or he stays in prison."
Chris Mullin, the Labour MP for Sunderland South who championed the cases of the Birmingham Six and gave advice to those working for Mr Nicholls, says a further problem occurs when an innocent man is finally released. Whereas someone leading up to release from a life sentence would be gradually reintroduced into society through courses and increased liberties within prisons, those who are found innocent on appeal are immediately pitched out into the world.
"This can have disastrous results," said Mr Mullin, "They find it impossible to cope. I think this is the greatest unresolved issue in this area."
Just how well Paddy Nicholls learns to cope remains to be seen. Certainly, he can count on the continued support of the informal network, if not on any help from the system that wrongly imprisoned him for so long.