Duncan Smith votes with traditionalists on Section 28

Iain Duncan Smith undermined Conservative attempts to shrug off its image as the "nasty party" last night when he voted to restore Section 28, which makes the promotion of a homosexual lifestyle by local authorities illegal.

Divisions in the party were laid bare when more than 70 Tory MPs, including 13 frontbenchers, voted to bring back the controversial clause, while 23 Conservatives, including the frontbenchers Tim Yeo and Nigel Evans voted against.

Mr Duncan Smith's backing for the clause, in a free vote, was immediately condemned by modernising Tory MPs and gay rights groups.

Stonewall accused him of joining the "bigots" and of being a member of "a small, sad and isolated axis of prejudice".

John Bercow, the leading Tory moderniser who voted against the amendment to bring back Section 28, described Mr Duncan Smith's vote as "a desperately backward step". He said: "It's very sad and rather shocking that Iain voted to reinstate a thoroughly offensive piece of legislation. I applauded Iain when he said that the Conservative party should review its stance on Section 28 because Section 28 sent out a message to gay people that Conservatives disliked them. That was true then and it is true now."

The Conservative leader was one of 77 MPs ­ most of them Tories ­ to back the restoration of Section 28 to Welsh and English law. The move was defeated by a coal-ition of Labour, Tory and Liberal Democrat MPs.

The frontbench Tories, Michael Howard and Michael Ancram were among those to vote with the party leader for an amendment to the local government bill tabled by the former Home Office Minister Ann Widdecombe.

During a heated debate, Conservative MPs openly clashed in the chamber. Edward Leigh, the chairman of the public accounts committee, said that Section 28 should be restored because homosexuality was "wrong".

"The reason I have put down an amendment to retain Section 28 is that I believe it is right and it represents the views of a majority of the British people," he said.

Miss Widdecombe, who has been a staunch opponent of liberalising the law on homosexual rights, was backed in the debate by Julian Brazier, the frontbench Tory MP for Canterbury and Andrew Selous, the MP for South-West Bedfordshire.

"The central issue is the sexuality of children, irrespective of heterosexuality or homosexuality," Mr Brazier said.

Michael Portillo, who has criticised Iain Duncan Smith's leadership, made a conspicuous appearance on the Tory benches but in the end failed to vote.

The Tory frontbench, including David Davis, the former party chairman, attempted to unite the divided party ranks with a "compromise amendment" which would reform sex education in schools. The amendment would have made it a legal obligation to give parents a right to a ballot on the materials used in their children's sex education.

But this was defeated by 356 votes to 127 and five prominent Tories including Archie Norman, MP for Tunbridge Wells, and John Bercow voted against.

Edward Davey, the Liberal Democrat local government spokesman, attacked the Tory plan for ballots as a 'recipe for homophobic behaviour on a grand scale."