Most old fighters come back because they are broke, bored or miss the limelight. Mark Prince has a far more compelling reason.
Before his retirement with a knee injury 15 years ago, Tottenham's Prince had an impressive career as a light-heavyweight, holding both the IBF and WBO Inter-Continental titles and fighting for a world championship in was to be his only defeat in 21 bouts. That was back in 1998.
His life was to change dramatically eight years later on the afternoon of Thursday 18 May 2006, when his 15-year-old son, Kiyan, a prodigiously talented young footballer on the books of Queens Park Rangers, was brutally murdered outside the gates of his school in Edgware, north London, the innocent victim of a knife crime for which his attacker, aged 16, was jailed for life.
The distraught Prince was instrumental, along with the then mayor of London, Ken Livingstone, in lobbying for knife crime to be introduced into the Violent Crime Reduction Act. He also set up a charitable foundation in memory of his son with the aim of campaigning in schools, prisons and the community, as well as counselling bereaved families similar to his.
However, this fight has not proved enough, so he has resumed his career with a fight which he hopes will raise both the profile of the Kiyan Prince Foundation and money for it. On 1 March, nine days short of his 45th birthday, Prince steps back into the ring at London's York Hall to contest the vacant WBU European cruiserweight title against the Czech Jiri Svacina, a prelude, he hopes, to another world-title shot this summer.
He has never stopped training, and proved his fitness with a quietly arranged winning warm-up bout late last year. He claims he is as mentally and physically prepared as he has ever been, driven by the desire to keep alive the memory of his son and highlight the horror of what happened to him, and others.
"Boxing helped me get through every day after Kiyan was killed," he says. "At the time I didn't think I could survive. I was sure I was going to do something crazy to get revenge, because there was hatred in my heart. But I asked God for help and saw I had to do things a different way. That was to share my experience with others. "I went into the streets and the schools and prisons. I spoke with gang members and told them of the hurt they were causing. I like to think I opened some eyes. Some seemed to look up to me because I was a boxer. Some even swore never to carry knives or guns again."
Now, he says, the Foundation must be kept in the spotlight, and his return to boxing is part of it. "I hope by doing this I can help spread the message and make street crime unfashionable, and say to them, 'You know, this ain't cool'. Some kids see carrying knives as a badge of honour, but I tell them it's one only a fool would wear."
Kiyan died from a stab wound to the heart after going to help a friend who was being bullied, and trying to break up the fight. Kiyan was wearing his QPR shorts and other friends said later that he was jumped on as he walked away, and that his last words were: "Please don't let me die... tell my mum I love her".
"I was so proud of him," says Prince. "We had just been down to the QPR ground. They wanted to sign him as a pro and talked of what a great future he had. They said he was the next Theo Walcott. He was growing into a fine young man, quiet and shy but full of character."
The boy who stabbed Kiyan, Hannad Hassan, is a Somali refugee who was said to be obsessed with gang culture. He received a life sentence, but Prince objects: "My boy was 15 years old. His killer will spend less than that in prison. That's not life."
Prince has five other children and his son Malek, 16, is also having trials with QPR. "People there, including Harry Redknapp, have been very supportive, and there is talk of staging a world-title fight there this summer after I win this one. I'm not a guy with delusions of grandeur. I'm a real fighter. I'm also a father who lost his son at the hands of another kid with a knife, and I want to make something good out something horrible and traumatic.
"When I was fighting before I didn't enjoy it so much. It was all too intense. Now I'm relaxed, sure of myself. I'm more mature. Age is irrelevant. I am going to be the Bernard Hopkins of the UK. I have a warrior spirit because of what I've gone through.
"So you see it's important that before I hang my gloves up again this mission has to be completed, because this is about more than the belts, or the glory. It is about promoting this charity and helping kids to come and work through our projects and programmes and be changed into new and different young people. People like Kiyan."
For more information about the Kiyan Prince Foundation visit: www.kiyan.org