East Worthing and Shoreham's Tory MP Tim Loughton came under attack last night in a damaging party rebellion over adoption.

The shadow health minister had to defend his party's decision to impose a three-line whip opposing plans to allow gays and unmarried couples to adopt.

Horsham MP Francis Maude was one of eight senior Tories who revolted against party leader Iain Duncan Smith, along with former leadership contenders Michael Portillo and Ken Clarke.

A further six shadow Cabinet ministers, including Arundel and South Downs' Howard Flight, were among the 35 Tory MPs who did not register a vote.

Others included Mid Sussex's Nicholas Soames, Bognor and Littlehampton's Nick Gibb and Chichester's Andrew Tyrie.

Early yesterday, leading shadow Cabinet moderniser John Bercow had quit over the decision to deny Tory MPs a free vote, calling it an issue of conscience.

In the Commons, Mr Portillo - a close ally of former shadow foreign secretary Mr Maude - turned these words against Mr Loughton.

He asked how Mr Loughton would have felt if he had been forced to give up his front bench job so he could vote with his own conscience.

Mr Portillo also turned Mr Duncan Smith's Tory conference speech, in which he stated that Britain had moved on in the past 20 years, back on Mr Loughton.

He asked why, if this was the case, the Tories had been put on a three-line whip for the vote as a weapon in a second exchange with Mr Loughton.

Mr Loughton replied he believed there was no middle way and the Tories must resist adoption by unmarried and gay couples.

He said the leadership's view was motivated by the desire to provide the most stable future possible for children being adopted. Married couples were likely to stay together longer than unmarried couples.

The remaining Sussex Tory MPs - Eastbourne's Nigel Waterson, Wealden's Charles Hendry, Bexhill and Battle's Gregory Barker and Worthing West's Peter Bottomley - voted with Mr Duncan Smith.

But the proposal to extend the adoption rights to gays and unmarried couples won a 199 majority and will tonight return to the House of Lords.

Hastings Labour MP Michael Foster, who was joined by Hove MP Ivor Caplin and Brighton Pavilion MP David Lepper in supporting the proposals, warned young children would continue to "languish in care" if adoption remained restricted to married couples.