The Conservatives have revealed a compromise policy to avoid a damaging row over Section 28.

The party's local government spokesman, David Davis, released details of an alternative to the rule which bans the promotion of homosexuality in schools.

The government is set to overhaul the controversial laws which were created by Margaret Thatcher.

Tory MPs will be given a free vote on an amendment to the Local Government Bill in a bid to stave off an embarrassing revolt.

The amendment, supported by the Tory frontbench, gives the force of law to existing government guidelines on sex and relationship education.

The rules - which prohibit the stigmatising of any particular sexual orientation - highlight the importance of marriage.

Parents would be allowed to view any teaching material to be used in sex education classes.

If there were a significant number of objections a ballot of parents would be held to decide the issue.

The proposal will be tabled in two weeks' time as an amendment to the bill - although the party accepts that Labour's huge majority means its bid is likely to fail.

Davis said: "Our number one priority is to offer children genuine protection and to strengthen the rights of parents when it comes to the way children are taught about sex in our schools."

"That is what really matters to families up and down the country. It is an important issue that goes beyond party politics."