A man at the centre of the row over sex offenders in schools says he is not a paedophile and his relationship with a 15-year-old was not against her wishes.
William Gibson, 59, was suspended from Portchester School in Bournemouth last week after his 1980 conviction for indecently assaulting the girl emerged.
But Mr Gibson said that until the girl was 16 they did not have full sex. They were later married for 19 years.
Chancellor Gordon Brown said the row over vetting had to be "sorted out".
Mr Gibson is one of three offenders it has emerged were cleared to work in schools by the Department for Education (DfES).
Education Secretary Ruth Kelly is now carrying out a review of the number of registered sex offenders teaching in schools in England and Wales.
She is due to make a statement to MPs on Thursday.
Mr Gibson told BBC Radio 4's Today programme: "My experience was I did nothing against the girl's wishes when I had this affair.
"When the case came to court, the prosecution read out a statement to say that she was happy with what had happened."
But he admitted the relationship should not have happened, and said he had not been thinking clearly at the time due to the process of going through a difficult divorce.
"The relationship with the girl certainly should not have happened, but I was down and out, weak from the break-up of my marriage and I needed someone I could talk to."
He said he had apologised for his actions, adding: "I can't ever see myself transgressing again.
"I appreciate the concern that parents have and I think they are right in having those concerns," Mr Gibson said.
"But I think they should look very closely at the facts relating to my own case."
Mr Gibson said he was questioned for two-and-a-half hours by DfES officials before being cleared to teach.
But he told Today that he thought anyone who had done anything to physically or mentally harm a child should never be allowed to work in a school.
The father-of-three said his children had not taken a negative view of him after the details of his case were revealed.
"I'm just trying to let the children see that dad is not the sort of bad person that everyone in the press is suggesting he is."
But he added: "At the moment I don't have a job, I have no income, I've no capital, I have nowhere to live, I've had to leave my rented accommodation because I was fearful for my life because I was described by the press as a paedophile.
"I could have been stabbed or hit with a baseball bat and killed, and my three children who I love dearly... would not have a father."
Chancellor Gordon Brown told GMTV that a "far better system" for vetting teachers would be introduced.
"This has got to be sorted out because I understand, as a parent, the worries of parents. I think we all do," he said.
Health Secretary Patricia Hewitt said legislation being brought forward, based on recommendations from the inquiry into the Soham murders, would also cover health professionals.
Ian Huntley murdered 10-year-olds Holly Wells and Jessica Chapman in Cambridgeshire in 2002.
It emerged during his trial that he had been able to get a caretaker job at a college on the same site as the girls' primary school despite a string of sex allegations against him.