The 11.20am train from London Marylebone to Bicester North has become a regular journey for Wendy Cohen. About once a week she makes the one-hour trip through the rolling Oxfordshire countryside to visit her son.
Her destination is not so picturesque. HMP Bullingdon may be surrounded by beauty, but its grey high walls, topped with barbed wire, are not welcoming. After Ms Cohen shows her passport and passes through the metal detectors, is led by a guard through three imposing steel gates and passes the sniffer dogs without cause for concern, she meets her 21-year-old son: Prisoner MW5897, incarcerated for a murder he swears he did not commit.
Sam Hallam was convicted in October 2005 for the murder of Essayas Kassahun, a 22-year-old Ethiopian trainee chef who was beaten to death in October the previous year by a gang of youths. But Sam says that not only did he not attack Mr Kassahun, but that he wasn't even at the place when the crime took place.
For the past five years he has protested his innocence from behind bars. On the outside, a protest group, led by Paul May – the man who successfully campaigned against the wrongful convictions of the Birmingham Six and the Bridgewater Four – has been mobilised.
They say they have uncovered new evidence: witnesses who are willing to testify that Sam was neither involved in the killing nor at the scene. In February last year they presented it to the Criminal Cases Review Commission (CCRC) and in September a review of Sam's case began. If the CCRC agrees that Sam's conviction could be unsafe, it can recommend that the Court of Appeal quash it.
While this is the hope that Wendy clings to, with one failed appeal already behind them, she is understandably not overly confident. "I have no faith in the system," she says. "I do not allow myself to say 'when' Sam is coming out, I only say 'if'. And if it does not happen this time we will just keep fighting, because my son is innocent."
Inside Bullingdon's large visiting room Sam greets his mother with a hug before settling down at the small table. He explains that he has dressed for the occasion, wearing trainers, jeans and a jumper rather than the shorts, vests and flip-flops that are ubiquitous on his wing. Only his hi-vis orange vest marks him out as a prisoner.
"The campaign really keeps me going," he says. "My mum and my family and friends keep me up to date with what is going on and being in here would be much harder without knowing people are fighting for me on the outside. I do have good and bad days. Sometimes I get angry about being in here for something I didn't do, but most of the time I just put it out of my mind. I am confident the CCRC will realise there has been a mistake."
Sam, from Hoxton in east London, was arrested on 20 October 2004, convicted at the Old Bailey on 26 October 2005 and sentenced to life in prison with a recommended minimum tariff of 12 years on 23 November that year. In the crowded waiting room at HMP Bullingdon, Wendy recalls the emotional impact it had on her.
"When he was convicted I couldn't even go into the courtroom. I couldn't believe the mistake they had made. After that I did not come and visit him for three weeks. I couldn't. I pretended he was not here. When I finally came I sobbed all the way home. Now the visits aren't so hard and I look forward to them. Me and my whole family are doing this sentence with Sam and I tell my self that as long as Sam is strong then I should be strong too."
Sam says he is supported on the inside by prisoners who believe his innocence. Much of Wendy's strength and support comes from her campaign group, Justice For Sam. Every last Thursday of the month the group of about 10 meet at St John's Community Hall, a small green hut surrounded by east London tower blocks.
The meetings consist of ideas to raise money and awareness for Sam's plight. Benefit nights and marches have done this and, on Monday, they plan to hand a petition to Parliament, protesting about the amount of time it has taken – seven months – for the CCRC to open a review into his case.
It has even attracted celebrity endorsements. Acclaimed actor Ray Winstone has thrown his weight behind the campaign, saying: "I cannot for the life of me, putting myself in the place of a juror, see how I can come to the conclusion of guilty. There were no forensics to link Sam to the crime and no CCTV of him even being in the area."
Yet he was convicted primarily on the strength of an eyewitness statement which named Sam as being at the scene. Later in court the witness said that she could not be sure if the man she saw was Sam, and added: "I was just looking for someone to blame on the spot really."
Wendy says she still finds it difficult to believe how that witness, who cannot be named, put her son's name in the frame for a murder he did not commit. "How could she do that? She admitted later that she wasn't sure if it was Sam, so why did she go to the police and say that in the first place?"
Sam's visiting hours are between 2pm and 4pm, six times a month – a number he has accumulated due to his enhanced status gained through his almost unblemished behaviour record in jail. This status also allows him to stay on the enhanced wing of the prison, which means a television and Playstation in his room, the right to wear his own clothes, as opposed to a prison-issue uniform, and four nights a week out of his cell – "association time".
He also spends time reading about other miscarriage of justice cases that have been quashed. He displays intimate knowledge of the cases of Barry George, Sion Jenkins and Sean Hodgson and adds: "I read about any miscarriage case I can. It gives me hope."
This is Sam's third prison in five years. He left Feltham Young Offenders' Institute upon his conviction and moved to Aylesbury YOI before being transferred to Bullingdon, an adult male prison, when he turned 21. At Feltham he gained qualifications in English and Maths and in Bullingdon he is in the process of completing an NVQ in printing and works in the prison printing room, for which he earns £9.50 per week. His time at Aylesbury was unhappy. He said: "The regime there was very different to here. We would only get one night a week out of our cell. Every other night we were in our cell from 5pm until morning. It gives you too much time to think. Here I have things to occupy myself. I go to the gym, I play pool or I go for a run in the yard. but at the weekends, when we don't get as much time out, it can be hard. There is more time to think."
Last week Sam received his first visit from the CCRC and was interviewed about his case. Despite the fact that the commission refuses to set a deadline for when they will complete the review into Sam's case, he has already dared to dream of life on the outside.
He added: "I miss normal things like my friends and my family, but I've also started thinking about simple things. They brought me to Bullingdon in a taxi, rather than a prison van, and it was the first time I had sat in a car for four years. I haven't crossed a road for five years, or licked an envelope. And, before I came to Bullingdon and started working in the printers, I hadn't opened a door for four years."
As well as the minor things, there have also been major landmarks Sam has missed while in prison. He could not celebrate his 18th or 21st birthdays and he was not allowed to attend the funeral of his grandmother in November last year.
Wendy said: "Sam and his gran were very close and it broke my heart that he couldn't be there to pay his respects. But it was probably a good thing. I don't think we could have coped with seeing him on the outside and then have to watch as they take him away from us again."
One of the most perverse facts of Sam's situation is that, because he will not admit his crime, if his conviction is not quashed he will struggle to ever gain parole as the parole board take a dim view of those who do not accept their crimes and see them as prisoners yet to be rehabilitated. Sam says he is aware of this, but is adamant: "I will not admit to something that I did not do."