However, moves by a group of Labour MPs to put an age limit of 18 on all relationships between teenagers and authority figures will muddy the waters of the debate.
The vote to equalise the age of consent seemed a foregone conclusion last night, with many MPs promising to return from constituency weeks to vote in favour of the move. But an amendment, signed by more than 30 members, calls for a new ban on all sexual relationships where one party is in a position of "authority, influence or trust".
Gay rights campaigners said the move would criminalise young adults unnecessarily, and that a definition of what constituted influence or trust would be hard to reach.
But Joe Ashton, the Labour member for Bassetlaw, who is proposing the amendment, said it would reflect the aims of Sir William Utting's report on children in care.
"If a teacher has an affair with a 17-year-old boy or girl, that's fine, except if the pupil is at his school. That's the distinction which I think parents would be very much in favour of," he said.
Ann Keen, the Labour MP for Brentford and Isleworth, will propose the amendment to the Crime and Disorder Bill which will reduce the age of consent to 16. "Let's get real," she said. "What right have we got to interfere with people's lives?"
She said the Home Office had agreed to review the law on adults in positions of trust in the light of the Utting report.
Gay rights campaigners say their fight for equality will go on, though. They will continue to argue for legal rights for unmarried partners, for an end to the ban on homosexuals in the armed forces and for new laws to prevent homophobic bullying.
Outrage! will now step up a campaign to lower the age of consent to 14. Its director, Peter Tatchell, said gay men were still being prosecuted under the provisions of the 1885 Criminal Law Amendment Act, which was used to imprison Oscar Wilde for his relationship with the Marquess of Queensberry.
The law against buggery, which originated in 1533, was still used regularly, he said, while a vagrancy law passed in 1898 to protect young girls from older men was now mainly used to prevent gays from "cruising" in public places.
"MPs planning to vote against the new age of consent should ask themselves this question: `If you had a 16- or 17- year-old gay son, would you want him put in prison for a consenting relationship?'"
Ann Widdecombe, the Conservative frontbencher and MP for Maidstone and The Weald, said she would be voting both against the move to cut the age of consent and against Joe Ashton's amendment.
"We all know little boys are attractive to the sort of older men who have those sort of inclinations, and I am not sure this will do anything to protect them," she said.