Labour rebels push Speaker to the brink of humiliation

Government narrowly escapes defeat over arrest of Tory frontbencher

The Commons Speaker, Michael Martin, suffered another blow last night when his proposal for an inquiry into the Damian Green affair descended into farce. Tories and Liberal Democrats vowed to boycott his plan for an MPs' investigation into the police raid on the office of Mr Green, the Tory Immigration spokesman.

The Speaker is under pressure to stand down before the next election, and there was growing speculation at Westminster last night that he will do so. The Conservative and Liberal Democrat leaders, David Cameron, and Nick Clegg, declined to express confidence in Mr Martin yesterday.

The Government only survived a demand for an inquiry into the wider implications of the affair – including the actions of the Home Secretary, Jacqui Smith, who insists she did not know Mr Green would be arrested – by the skin of its teeth. That proposal was rejected by 285 votes to 281, leaving the Government with a wafer-thin majority of four.

Twenty-nine Labour MPs voted against the Government, including the former ministers Charles Clarke, Keith Vaz, Denis MacShane and Alan Williams, the longest-serving MP. The backbench rebellion was provoked when ministers stalled an MPs' inquiry into the police search of Mr Green's Commons office. The frontbench Tory is being investigated over a stream of leaks to him by a Home Office civil servant.

Last week, the Speaker told the Commons he was setting up a cross-party inquiry into the case, which would report as soon as possible. But yesterday a government motion said the investigation should be delayed until after the police investigation. It also said the committee of inquiry should have a Labour majority.

MPs approved the Government's proposal for a limited inquiry by 293 votes to 270, only for the Tories and Liberal Democrats to announce that they would play no part in it. In a highly-charged three-hour debate, MPs from all parties accused the Commons Leader, Harriet Harman, of defying the wishes of the Speaker.

Theresa May, the shadow Commons Leader, said: "This committee would be stymied in its remit, packed with a government majority and be silenced at the time when it is needed most." But Ms Harman insisted that the Commons had to avoid the "accusation or perception that we are in any way interfering with or breathing down the police's neck".

*Labour has narrowed the Conservatives' lead to just four points in the latest opinion poll, which saw public support for the Tories fall below 40 per cent for the first time since April. The survey by Populus put the Conservatives on 39 per cent and Labour on 35 per cent.