'I DIDN'T, and still don't, see the need to make the choice between my son and my husband,' says Sophie of her husband Jeremy. Three years ago, when she had just begun a relationship with him, he was convicted of a sexual offence against a child. Now Sophie, Jeremy and their own baby are at the focus of an emotive debate over whether sex offenders should be expelled from their families when the families want them back.

There are thousands of couples like Jeremy and Sophie. At the heart of their story is the issue of whether sex offenders can be cured. Some experts are convinced not only that this is possible, but that the best hope for successful rehabilitation lies in keeping such families together; it is also better, they say, for the children to grow up in a stable, loving family with both parents.

A year ago Sophie and Jeremy seemed to have everything to look forward to. They had married, and Sophie had started a business designing dresses; Jeremy was an electrician. They had bought a house and Sophie was expecting a child. But the picture now looks very different.

Sophie and their son, Mark, born just before Christmas, have moved from Cheshire to the Midlands and she avoids going to the park because she cannot bear to see happy families together. In the months since Mark's birth, Sophie and Jeremy have waged a bitter struggle with the social services to keep their family together. Jeremy has been forced to leave home, and at one point all three fled abroad, fearing that Mark was about to be taken by the authorities; they returned only when extradition papers were about to be served.

Their problems began in 1989 when they were baby-sitting for Jeremy's sister; Jeremy seemed to have been gone from the room for an unexpectedly long time. Sophie went to the four-year-old boy's bedroom and walked in on a shocking scene: it was, she says, 'like witnessing a murder'.

Jeremy was standing, stroking the sleeping child's leg and masturbating. Hearing Sophie come in, he pulled her on to the bed and had sex with her.

Sophie did nothing at first. 'The overwhelming emotions were shock and fear. How do you tell a child's mother who you're very close to that you've seen her brother abusing her child?' she asks. But she kept a close eye on Jeremy until, two weeks later on an outing in the car, she noticed that Jeremy had his hand down the child's shorts.

She told him to put the boy in the back seat and took the child straight home. A week later she moved all Jeremy's belongings out of their home, changed the locks and told his sister what she had seen. His sister called the police.

'I told the parents rather than the police, as I thought it was their right, but I'm being criticised for that now. I just wish I'd told the parents earlier,' she says. At his trial, Jeremy pleaded guilty and he went to jail for four months for indecent assault. 'It was as though I was throwing my hands up in the air and saying: 'Please help me,' ' he says.

Sophie and Jeremy married just before the court case: 'I didn't want to kick him into the gutter like everyone else,' she says. Last year Sophie discovered she was pregnant, and got in touch with the social services to tell them of the situation - wanting, she says, to avoid them finding out through gossip. Jeremy had received therapy in prison and had spent hours talking the subject through with Sophie, leaving her convinced that he was no longer a risk. She felt they had nothing to hide and that if she were not honest with the social services they would be able to break up the family. 'From the beginning I made it clear that I wanted my husband to remain with us. Social services have made our lives an absolute nightmare.'

But convicted of a sex crime, Jeremy is categorised for life under the Criminal Justice Act as a Schedule One offender, which means that the social services regularly assess him. Three weeks before the baby was born it was placed on the child-protection register. After Mark was born in hospital, Sophie saw a note in red pen on the end of her bed reading: 'Patient's husband has committed an act of indecency against nephew aged four. Social services to be informed if mother attempts to leave hospital.'

'Everyone knew who I was and what was going on,' she says. 'When Jeremy came to visit me, all eyes were on him. I spent almost all of the time in hospital in tears. It was so embarrassing; I felt like a freak. I was terrified a social worker would take Mark away, so I used to take him to the bathroom with me. People used to say: 'Your baby looks different to the other babies.' Of course he did - he was older than them, because I was being kept in hospital while they worked out what to do.'

At a court hearing eight days after he was born, Mark was made a ward of court and Jeremy told to leave home immediately. He went to live in a caravan on his own. 'I was told that if I was not prepared to leave Jeremy they would take Mark away from me,' Sophie says. But she is adamant that she loves and trusts her husband and believes he is no longer a threat to children. 'I'm convinced Jeremy is no threat to my baby. I would know the signs, and anyway there is no way I would put my child at risk. I was, after all, the one that shopped him and the one who went to the social services in the first place to tell them I was pregnant.'

In February, Jeremy and Sophie took Mark abroad as they feared the social services were about to take him into care. Jeremy quickly found a job. But the social services took Jeremy's father to court to force him to tell them where the family was staying, and they returned to Britain. Sophie moved to a rented house in the Midlands because she could not face the gossip and the attentions of the social services, who continue to control Jeremy's access to his son.

She, too, is under suspicion. Jeremy told the police that Sophie had encouraged him to commit the crime, but because he pleaded guilty she did not find out about his statement until recently. He now denies that she had anything to do with his offence, and says he was trying to spread the blame.

Jeremy has been encouraged to attend a course at a private clinic - but the cost could be pounds 30,000 for a year, which might have to come out of his own pocket. He believes that the purpose of the proposal is to enable the social services to pass the responsibility on to someone else.

Jeremy and Sophie complain that they have been given no credit for making the initial approach and co-operating. They had to make a list of responsible friends who would oversee Jeremy's access to Mark on behalf of the social services. One couple was told by a social worker that Jeremy was a risk to any child and it was a risk they should not be prepared to run.

Another friend, a trainee solicitor, says: 'Anybody who molests a child, and it makes me shudder to think they can, should be punished. But I do believe that Jeremy is a very remorseful person and feels great shame for what he did. I don't feel he would commit a crime like that ever again. He just isn't being given a chance. It all seems so wrong.'

Like many sex offenders, Jeremy was himself abused as a child: one theory is that such people are liable to repeat the behaviour under stress, but that the pattern can be changed with therapy. At the time he committed the offence, Jeremy's building society was calling in a large loan on a house he was renovating and he was in danger of bankruptcy.

Shirl Marshall, of Aftermath - a support group that offers counselling to the families of men convicted of serious offences - has seen this pattern of sexual abuse through the generations before. 'It would often be foolish to allow the man to return to his family, whether against their wishes or not,' she says. 'But this is a case where the man has now dealt with his own past abuse. He is responding to counselling and little Mark is suffering far more than he would be doing if his father was at home. All too often the social services are operating out of their depth and they get it wrong. They are operating in areas they are not qualified to deal with.' Ms Marshall says that the hard line taken by some social services departments may perpetuate the problem rather than help to solve it.

Childcare professionals agree that the dilemma in such cases is where to draw the line. No one wants to put children at risk of abuse, and everyone agrees that some sex offenders are beyond help. It is possible that, however genuine Sophie is, she could be wrong about Jeremy; it is possible that Jeremy has overestimated his own progress.

Cheshire social services would not comment directly on the case, but a spokesman said: 'Local authorities have a duty to investigate and take action where matters of grave concern are brought to their attention. It is for a court to decide a course of action which is in the best interests of the child. This may not accord with the perceptions of the parents.'

Sophie and Jeremy are convinced that the social services want to split them up permanently. They have now been to court eight times. 'We have been given no opportunity to say anything yet. The only input we have had has been statements written for us by our barrister. I just can't believe that in a civilised country people can be punished for a crime which might happen in the future,' says Sophie.

The case hinges on what is best for Mark, and that is the question exercising the professionals. 'What will Mark say when he grows up to find that his father has been kept away from us?' asks Sophie. 'I know he's no risk, but how do you prove that?'

Aftermath can be contacted on 0742 326166.

Sophie, Jeremy and Mark's names have been changed for legal reasons.