The prisoner and the neurosurgeon

A library, a doctor and sheer will freed Kevin Callan after four years wrongly convicted for murder Kevin Callan: of Dr Phillip Wrightson, who helped him from New Zealand, he says, `I can't explain how I feel about that man' Photograph: Howard Barlow `E...

When the police came to arrest Kevin Callan for the murder of his girlfriend's four-year-old daughter, he was in the kitchen waiting for the funeral directors.

"They said, `Can we have a word with you in the kitchen please?' I was stood against the kitchen unit. One of them said, `I'm not happy with your explanation and I'm arresting you on suspicion of murder.' And I just slumped to the floor."

As he was being led away, Callan wondered about the "explanation" the police inspector referred to, the one the inspector was not happy with. The girl, Mandy, had collapsed in the bathroom some days earlier. Callan had attempted mouth-to-mouth resuscitation. He had called the emergency services. He had not given an explanation: no one had asked him for one. Until now.

"They took me to the police station and subjected me to an absolute verbal hammering. It was horrendous. I could not believe what they were saying to me. They said, `There's no other explanation for it. There was only you there. You had to do it. You lost your temper. You shook that child to death.' "

Four years later, Kevin Callan sits in an armchair by the net-curtained window in the front room of his sister's semi in Dane Bank, Manchester. He has served four years in Her Majesty's Prison, Wakefield, years in which Callan - a lorry driver who left school without O-levels - applied himself to medical textbooks, to legal papers and to endless letter-writing until his innocence was beyond doubt. When we meet, it is five days since his appeal passed unopposed through the court; five days since he sat in the dock with Securicor guards on either side and said to them at the end of it all, in disbelief, "Is that it now? Can I go?"

He says he is still "dazed" and it shows. There is a free-flow of people through the house: his sister Gayle; his brother-in-law, Keith, who is "totally mental"; his giggling teenage niece; his friend Kirsty and her two kids, one in a Ryan Giggs shirt. The phone rings a lot - his solicitor's assistant in Salford, his mother in Wales. And during most of this, Callan remains seated, shattered, tapping his cigarettes into a glass ashtray on a stalk.

His release coincided neatly with his birthday. There is a vast chocolate egg on the sideboard and a shiny, helium-filled balloon with a trailing ribbon bumps against the ceiling in the corner. It says, "To the birthday boy". Callan was 37. He looks older, though. Things have got to him - bereavement, injustice, prison. Prison has pulled his skin tight against his cheekbones. His sister Gayle says: "You were on a visit, watching for Kevin coming out, and everyone had got the same face: drawn, the same colour and the same expression. They were like they'd been wound up." His girlfriend, Lesley Allman, stood by him and gave evidence at his trial. But during his imprisonment, they split up. Callan's hair, shot through with grey, is long at the back. It has been coming out in clumps.

He is in a process of adjustment. There is much to get used to. Ready- made cigarettes rather than roll-ups. Tea out of a mug rather than a plastic beaker. And the fact that he can have the tea and the cigarettes whenever he wants them. He keeps waking up at odd times. Also there is a motorway running past the back of the estate. It was not there last time he was here. He apologises to me for the persistent growling coming from his stomach. His system is still trying to remember how to cope with proper meals after four years of prison food - the circle of spam, the slab of corned beef with the quartered tomato.

Sent to jail, Callan wrote "Innocent" in orange marker pen across the official card with his name on, by his cell door. The card was swiftly replaced. This time he wrote beneath the name, in smaller letters, but in the same orange: "And still innocent". And then he got on with proving it.

When he was released, some of the reporting in the papers warmed to the thought of the lorry-driver-turned-pathologist, a boffin among the lags. One report said his cell had been loaded from wall to wall with textbooks. This is not quite how it was. In many ways, the process was more arduous than that and called for greater patience. Callan will not now be setting up as a neurosurgeon. But he could possibly apply for a job as a saint.

His initial moves were muddled, panicked. He wrote first to the trial judge - "pages and pages. I didn't even know what an appeal was." He wrote second to the Queen. "I said, `I'm in one of your prisons and I would like you to be aware that I am innocent.' I knew the Queen wouldn't free me - though she could have, of course - but it was pouring out of me: this is wrong, this is wrong."

The judge forwarded Callan's case papers to his solicitors. "But they blanked me out, didn't take phone calls or anything." The 28-day period for lodging an appeal passed without his even realising it.

The only way forward now was to produce fresh evidence. He went to the prison library. "I saw a librarian from the outside, called Kate Smith. I said, `What have you got on injuries?' That's how green I was; I didn't even think to say `head injuries'. She said, `Look in the sports section, there's one there.' "

He took it back to his cell. "Mostly it was about broken toes, broken arms. But there was a little bit on haemorrhaging which was, as far as we'd heard at the trial, the cause of Mandy's death. Anyway, I realised this book was no good for me. I had to wait a week then, because you can only go to the library once a week."

This time, Callan asked specifically about head injuries. The librarian's computer search came up, almost comically, with Head Injuries: The Facts. Before he could even order this book, he had to put in an application to see a Senior Medical Officer. "He said, `What do you want it for?' I said, `I lost a child here. I want to know why.' They thought I might become a hypochondriac. But I went through it all with him and finally heokayed it."

Callan says that when he read Head Injuries: The Facts, he cried. "It was aimed at lay people - and there was what happened with Mandy. Black and white." He wrote to the book's author, Dr Phillip Wrightson. Even this was not simple. Dr Wrightson had emigrated to New Zealand. But he wrote back and a correspondence began.

For the first few months, Callan had no access to transcripts. He wrote down what he remembered from the pathologist's report, as it was conveyed during the trial. "Dr Wrightson thought a vessel had burst in Mandy's head. And that was before he saw any post-mortem photographs. This was on the evidence only of quotes I had given him from the investigation. He was that sure."

Mandy had cerebral palsy and a history of falls. On the day of her death, she had fallen twice: from a swing and on the stairs.

"Dr Wrightson wanted more stuff. I got more letters going. It was probably a load of nonsense, much of what I sent him. I sent him a Child Development Unit report on Mandy - whatever I could lay my hands on. But he was writing back to me and telling me that the evidence was there."

Callan fetches in from a box in another room the diaries he kept for four years in jail. They are thin, stapled booklets, a week to a page, handed out by the prison chaplaincy, with chocolate-box colour photographs on the covers: trees in autumn, smart English villages in summer, herons. He shows me the resolutions he inscribed at the beginning of each one. At the beginning of 1992 he wrote, in block capitals, "Truth". In 1994, he wrote, "Freedom and truth". On 1 January 1995, he wrote: "Go for full truth and freedom".

The diary entries he reads aloud are terse. Some record his frustration with the prison postal service: "Tapes arrived. Bastards won't let me have them." Others note meetings with the solicitor, CJ Malone, who took up his case in 1992. At some point, Gayle had sent Callan a cutting from the Manchester Evening News in which Malone was quoted, following a victorious but quite unrelated case, saying: "I have no doubt there are more innocent people in prison." Callan decided this was his kind of solicitor. His diary for 6 April 1992 reads: "Saw Campbell Malone. Very good. Sent letter to old solicitors regarding change."

CJ Malone was energetic in Callan's defence, liaising with Dr Wrightson and with a Home Office consultant neuro-pathologist, Dr Helen Whitwell. The judge in the Appeal Court praised both Callan and Malone for their "tireless research". But the pair were forced to question from time to time the pleasure Wakefield Prison was taking in their industry. Callan noted with bafflement the delays to his mail, the mysterious disappearance of bulky packages from Malone. "They got it into their minds that I was fighting the prison system. But it wasn't them who put me there and it wasn't them who were going to get me out. Each time they gave me nonsense, I walked away from it. I knew where I was going."

Shortly after his release, the BBC took him into a studio in Manchester for a satellite link-up with Dr Wrightson in New Zealand. Dr Wrightson's picture does not appear in the book Callan consulted, so this was the first time he had seen him. "He was winking, he was waving, he was fists up," Callan says. "I can't explain how I feel about that man."

Right now, he is filled with a kind of missionary zeal. He talks animatedly about a speech he is going to make at a public meeting in a room above the Wheatsheaf, a pub in Manchester. He is wondering whether the small protest group his sister organised on his behalf cannot be turned into something more solid, a campaign unit for the wrongfully imprisoned, with an office and sponsors.

But money is a problem. At the moment he is, as he puts it, "useless". He came out of jail with the standard issue £40 and spent nearly all of it immediately on clothes - two pairs of jeans, two shirts and (best of all) some underwear. "Everybody wears boxer shorts now, don't they? Well, I've got to catch up. I just wanted a pair of underpants." He gestures towards the kitchen. "They were ribbing me because I arrived here in prison underwear - Y-fronts."

I ask him if he is going for compensation. He says he thinks he ought not to talk about that now. "All I can say is, I've been wrongly convicted. And compensation won't give me four years back."

He intends to finish the book he started - 100 sheets of A4 rattled into the typewriter in his cell, "the story of all this, my feelings". After a while, fellow inmates began to call him "doctor". They would seek his advice on their headaches. "And I would say, `Probably the easiest way is, take your head off.' " Some of them asked him to help prove their wrongful imprisonment. One of the last entries in his diary - for 1 April 1995, written after the announcement from the Crown Prosecution Service that it would not oppose his appeal - reads: "Lots of mail. Card from Mum and Dad. Lads on wing overjoyed."

Gayle retrieves a greetings card from the cluster on the sideboard beneath the balloon and hands it to me. It is from the inmates on Callan's wing - all block capitals and exclamation marks, with many jocular references to smelly feet ("My feet stink," he says, laughing) and a neat gag in the middle about making a fresh start.