Our good friend the former convict

Criminologist Kathy Curran wanted to practise what she preaches – so she invited a repeat offender into her home. They say it's led to a unique and lasting bond

One of the family: Kathy Curran at home with 'Brian' and her two children (David Sandison)

Kathy Curran always checks the doors and windows before leaving her smart home just north of London. "I know all about security," she laughs. "I've been trained by the best." By the best, she means Brian, a career criminal who has spent nearly 30 years inside. She and Brian have formed an unlikely but remarkable alliance over the past eight years. It has culminated in his looking after her children and even going on holiday with her and her husband.

Kathy, a criminologist with a doctorate from Cambridge, specialises in the rehabilitation of repeat offenders. A brief spell in the Probation Service convinced her this wasn't the way to build up trust and really make a difference. She says you need to spend time with people, have a drink and a chat in the pub, take them shopping.

"Once you've established trust, people are more receptive and more likely to listen to advice."

The theory is one thing, but inviting a criminal into your home is quite another. "Getting that first job is key," she continues, "but in reality no one wants to employ an ex-offender. That's why I decided to do just that."

Determined to practise what she preached, she visited New Life, an organisation (now sadly defunct due to lack of funding) that helped former prisoners to learn the skills they'd need to gain employment. It was here that she first met Brian (not his real name). Eight years later , she's never looked back.

"He was very smartly dressed in a matching suit and tie, with polished shoes and slicked-back hair. But he looked really nervous, too," she recalls. "I told him I wanted him to come and paint the outside of my house."

"This was my first chance to earn clean money," Brian chips in. "I'd had it drummed into me that if I worked and paid taxes, I was a mug. Going out to earn money, before, meant I never knew if I'd make it home in the evening. So I felt utter relief when Kathy offered me this chance and I grabbed it with both hands."

Brian, now 50, reels off an impressive A-to-Z of his past offences – shoplifting, fraud, drug dealing, armed robbery ("just till money"), and "creeping". For the uninitiated, this is when you dress up as a window cleaner, for example, go into a commercial property and pilfer from people's coats and desks.

But by the time he was in his early forties, something was beginning to change. Grandchildren were being born and Brian hated it when they came to visit him in prison.

"It brought a tear to my eye, and I didn't want them growing up and ending up in my shoes," he tells me. "And something began working in the old grey cells that wasn't working before."

Poignantly, Kathy was also pregnant with her first child at the time. And although she never doubted her decision, the same could not be said of her husband, Charles, who positively blanched when she told him that an ex-offender was coming to paint the house.

Brian laughs: "He used to give me really funny looks when he came home from work. I think he was as unsure as I was about the situation."

Kathy continues: "After a month, I left Brian in my house alone as a kind of test. I knew he'd gone into my bedroom when I came home, as I'd closed all the doors. He said, 'But Kath, I've never been in such a posh house before!'"

She adds: "It didn't take my children long to realise he has a good heart, either. They are thick as thieves now and absolutely adore him. I know I can leave them with him any time."

Brian was born into a criminal family and grew up on a deprived estate in south London. All his school friends and their families were criminals of one kind or another.

His journey back from the criminal underworld has meant overcoming a number of hurdles. Opening a bank account was one of the first. He had only magistrates' letters as proof of identity, and when Kathy dragged him to a building society on Holborn high street, Brian panicked, turned to her and said, "God, Kath, last time I was here, I robbed the place!"

He procrastinated for years about getting a passport, but when Kathy invited him on holiday with her and Charles, he had no choice.

"I'd spent my whole life avoiding being identified, so I couldn't understand why I needed one, and I had to pay money for the bloody thing to boot," he says.

He'd never been abroad before, let alone on an aircraft. "He spent most of the flight cowering in the aisle at the back outside the toilets," Kathy says, "but once he'd had a taste of sun and sea, he loved it.

"We had a newborn baby by this time," she continues, "and we were knackered, and Brian, being used to prison hours, would be up at five playing with him and giving him his milk till I came down at six."

"I began to appreciate family life," Brian says. "It was a revelation to me. They showed me a way to live I'd never seen before. Most kids get a pat on the back when they come home from school with a gold star. All I got from my dad was a clout round the head and he'd say, 'Well, that ain't gonna earn you money now, is it?' But if I told him I'd nicked a lorry-load of stuff and sold it to the guy up the road for £300 he'd say, 'That's the way to go, boy.' That's how I was brought up."

Brian's journey going straight started back in 2004 and has taken enormous commitment to kick the habits of a lifetime. Over the years, Kathy and her husband have encouraged him to pass his driving test so he could buy a van and build up his gardening-and-decorating business. He still paints many people's houses in that same street.

"I've learnt social skills, too," he says, "and I know how to deal with situations in a rational way. I don't go off my head any more. I know there's always an alternative to violence. I've learnt family values and I realise you can create a good life for your children, even in deprived areas. I know you can work your way out of that without being a monstrous nightmare to society."

Brian continues to live on the same estate, but has nothing to do with anyone from his past. His partner has also begun to see the benefits of going straight. They share a lovely flat together paid for with "clean" money and which is their own to enjoy.

Kathy says helping Brian is the most important thing she has ever done in her life, but the benefits go both ways.

"He's a huge support to me, too. He helps with the kids all the time, he does lots of jobs round the house, and I know I can always rely on him."

"Everything's different now," Brian says. "We've got a fridge full of food, we have a nice home, and I have my van, my work and, most of all, my self-respect."

He adds: "In the end, my perseverance paid off, but that's because I really wanted that change to happen. If someone doesn't want to change, no amount of patience and persuasion can bring them round."

Kathy explains: "You can't just leave people when you've started them on a difficult path. You have to take the time to trust, encourage and nurture them. Brian is still the same person, but he now uses his entrepreneurial skills, his resilience and coping strategies in a positive way. It's a hard sell, though, and takes strength of character."