IT IS a question as old as the act of protest itself: “What price justice?” In the case of David Luxford, the answer is easy; £96,586.14. That is how much Luxford’s wife, Greer, spent in proving that he was wrongly convicted not once, but twice, of raping a 13-year-old girl.

Luxford, a family man with no previous criminal record, was languishing in prison, sharing a wing with the paedophile and former music impresario Jonathan King, when it first dawned on Greer to “go private” for justice. If you could pay for a second opinion from a doctor or fork out on private education for your child, why not hire a team of detectives to investigate your husband’s case?

Five months later, after almost three years’ of incarceration, David Luxford was a free man when the private investigation proved that he could not possibly have committed the crimes of which he was convicted. It was an inquiry that highlighted how very differently things can turn out for a defendant when there are the resources to conduct an exhaustive investigation.

Last month, Steve Green, the Chief Constable of Nottinghamshire police, provoked a political storm when he said his detectives couldn’t cope with an avalanche of murder inquiries that led to him farming out investigations to other forces. Did that mean that cases throughout the country were not being investigated adequately because of lack of resources? The police say no, but Greer thinks it may be. And for growing numbers of frustrated families, she believes going private for justice is the only avenue left open to them.

According to the bodies that represent the respectable end of the private investigation industry, more people are turning to them when they feel they have been wrongly charged or convicted. Legislation regulating all aspects of the security industry will focus on private detectives this summer, requiring them to apply for licences to be issued next year. Practitioners hope that will weed out their more unsavoury colleagues. And when that happens, private detectives believe even more people will feel confident enough to turn to them for help.

David Luxford had never imagined in his wildest dreams that his freedom would one day depend on the work of a gumshoe. Now aged 38, he was a postman living and working quietly in Orpington, Kent, when, in February 2000, he was accused by a 26-year-old woman of having raped her 13 years earlier. Greer, now 51, takes up the story.

“We had been out one night and when we came home there was a piece of paper that had been slipped under the door asking David to contact the Police Child Protection Unit in Catford,” she says. “There was no explanation and at first we were concerned that something had happened to our daughter, Sara.”

Sara, now 14, was away on holiday and the Luxfords were quickly able to establish that she was fine. The next day, Luxford contacted a friend in the police to ask what could be the matter. He was advised to take a lawyer with him when he went to see the child protection team.

When he turned up, frightened of the unknown, he was told that a woman — we shall call her Kimberley — had alleged that he had repeatedly raped her between 1988 and 1989.

“I listened to what they had to say and I took it all in and then I just burst into tears,” Luxford recalls. “It was as if my whole world had collapsed around me. I had done absolutely nothing wrong and here I was, 13 years after the supposed events, being asked to prove a negative. She had made all sorts of allegations against me and all I could do was say, no, I didn’t do it. But from the very start, I got the impression that the police believed her instead of me.”

After the interview, Luxford went outside and told Greer and his father, also David, what had happened. “I asked him straight away, ‘Did you do it?’ and he said ‘No’,” says Greer. “I believed him completely.”

The following July, after a five-day hearing at the Old Bailey, Luxford was convicted of two charges of rape and one of indecent assault. There was no medical evidence and no corroboration. The jury apparently believed that Kimberley was a better witness than Luxford. Sentencing was deferred for two months and then he was given a total of seven years in prison.

“It was her word against mine,” he says. “But whereas she came up with all these very emotional allegations in great detail, all I could say was ‘I didn’t do it’. When I was sentenced I tried to keep my composure but when they took me down to the cells I just burst into tears. I must have cried solidly for 12 hours.