Lee Walker was a 22-year-old student, on a night out with friends, when he was killed by a single punch. Four months on, his parents talk to Nick Morrison about why they are appealing against the killer's sentence and what they discovered about their son after his death.

PINNED to the back of his bedroom door, alongside the sheets of song lyrics, was a small square of paper bearing a quotation from James Dean. It read: "Dream as if you'll live forever; live as if you'll die today."

Lee's dream was to work in the movies. As well as the home movies he made with his friends, there are the books on film studies in his bedroom, some unavailable in this country and bought by mail order from the United States. Then there are the piles of scripts, and a letter to a solicitor asking how to stop his ideas from being stolen.

Neil and Diane Walker knew their only son was keen on films, ever since they had bought him a video camera for his 18th birthday. What they didn't realise was quite how keen he was. At least, not until after his death.

"It made me feel belittled, to not realise how into it he was," Diane says. "He was a quiet lad. It was sometimes hard to get a conversation out of him. They come in and they go their rooms and you get the odd word out of them now and again. You don't realise."

It was March 29 this year, and Lee had gone for a night out in his home town of Darlington with some friends from Capita, the company where he was working in his gap year. As he left the Bar Size pub in Skinnergate, he was confronted by Lloyd Smith.

Smith punched Lee in the face, knocking him to the ground. Lee picked himself up and went home, but later collapsed and was taken to hospital. He never recovered consciousness and died the following night. He was 22.

Earlier this month, Smith was jailed for two-and-a-half years for manslaughter, after what he admitted was a completely unprovoked attack.

Since Lee's death, Neil and Diane, both 45, have started to sort through his things, but it's proving to be a difficult task.

"There is a lot of work to look through. We haven't really gone through it yet," Diane says. "Whatever you were doing before goes out the window and you just end up sitting looking at it.

"The home movies are a Godsend, because you can see him moving and talking. I have to be in the mood, but it is nice to watch."

Among Lee's work is a series of cartoons, including one where his dad is depicted as "Army Neil", on account of his stint in the Territorial Army. It was a nickname Neil didn't know he had until he saw the cartoon. "He was dead then," Neil says.

"It was spot on. We used to go away every weekend, although we haven't bothered this year, and we used to say if there was any mess in the house... I used to say 'Three strikes and you're out'.

"The cartoon shows he knew we wouldn't throw him out. He was just making fun of it. He was very clever, very funny, very creative."

Neil and Diane, whose daughter, Stacey, 19, is at university, received a letter of condolence from Lee's tutor at Luton University, where he was studying creative writing and script writing. "He said Lee had the potential to go far, which is nice in a way, but sad in that you're never going to know," Diane says.

"What could he have gone on to? That is the sad part," Neil adds. "But it makes you proud to know he is a lot cleverer than we ever realised."

Neil and Diane sat through all of Smith's three magistrates' court appearances and one crown court hearing.

"Initially, it was because we didn't even know what this lad looked like. You have got to go and see who killed your son," Diane says. "Every time you go you hear something different to what the police told you, you are hearing more of the jigsaw put together."

Neil, a production operator at Cummins, adds: "When someone has taken your only son for no reason, it is important to see who has done it to try and find out why. You have got to. We wanted to see justice being done."

But the sentence left them feeling justice has not been done. Smith is expected to serve just 11 months. Diane says they are determined to appeal. They are also planning to join a campaign for stiffer sentences.

"We're just disgusted with it. It is a person's life, and he actually said Lee was blameless," she says.

"We know we're never going to get Lee back, but it has made us determined. It is sad that it is through this that we're doing it, but at least we're going to be doing something."

"Lee did absolutely nothing," adds Neil. "Eleven months. He will be out in 11 months. You can't put into words what such a loss means to the family. And for nothing, for absolutely nothing."

'You couldn't even call it a tragic accident," Diane says. "It is not like he has been killed in a car crash. There is a person there responsible for his actions.

"If it was just a kerfuffle, where did the force come from to break Lee's jaw? I want to go and see this lad and ask why, but I know I won't get an answer. I just need to know why he hit him. It goes through your head... "

Neil and Diane's house in Darlington was often a meeting point for Lee and his friends from school who called themselves the Waxers, and a few days after the sentence some of them came over once again.

"You feel sorry for them because you know they're upset, you know what happened has really affected them," says Diane. "They just can't believe it. They all think the world of him and they can't understand why someone has hit him, because they know he's not aggressive.

"We've missed them, because they have always come over. We've had letters from parents saying 'Thank you for having our sons over', and it has been lovely. They're lovely kids, well, they're grown up adults now, but I still think of them as kids," she smiles.

Diane, who has been off sick from her job as a sales rep at Glaxo since Lee's death, has started going to counselling, but nothing can make up for the fact your son died for no reason.

"It is indescribable what you are going through. A lot of the time I'm just numb, I don't feel anything at all. He did it for nothing, I just can't understand... ", she says.

"We don't come from that world of people. We just can't understand how someone could do that. I know he is my son and you think he is perfect, but he didn't have a bad bone in his body."

Neil adds: "We know it has happened for nothing and that makes us feel worse. If there had been a scuffle and Lee was involved, but for absolutely nothing... "

They may never know why their son died, but everything they have since found out has only reinforced their memories of Lee.

"We're proud of him, really proud," says Neil.

Diane adds: "He had lots of friends, he loved going out. The night he died he was doing what he enjoyed. He loved life, and he believed you should get out there and enjoy life, because you don't know what tomorrow holds.

"He has not been a bad lad. He was not into drugs. We haven't had any problems with him at all, which is one way to look at it. I just think he was lovely."