The moment anti-terror police raided top Tory's office inside Parliament

The exclusive picture shows for the first time the dramatic scene when counter-terrorism officers from Scotland Yard were allowed to rifle through the Shadow Immigration Minister's confidential Commons files.

A police officer, with his face obscured to protect his identity, furiously confronts the Tories who took the video film.

Visible in the picture is David Cameron's principal political adviser Andrew Mackay, who insisted on ensuring that a video record was taken of the unprecedented event. A female officer, wearing purple gloves, is on hand to take police photos.

Behind the camera was an unnamed Conservative party official believed to be the man who makes the "Webcameron" videos for the Tory leader. He and Mr Mackay had dashed over to Mr Green's office as soon as they were tipped off that Scotland Yard were on their way.

Police stunned Westminster last Thursday when they arrested Mr Green and held him for nine hours over Home Office leaks.

The Metropolitan Police faced an immediate backlash from the Tories and Liberal Democrats for the "disproportionate" decision to detain the frontbencher and to take files from his Commons office.

Commons Speaker Michael Martin is facing huge pressure over the decision to allow the police to search Mr Green's private documents and computer files. Today, Commons leader Harriet Harman held a meeting with Mr Martin's officials ahead of a special statement on the police action tomorrow.

Earlier today, a Conservative MP launched the first move in his bid to oust Mr Martin over failing to stop police raiding Mr Green's office.

Backbencher Richard Bacon was due to consult hundreds of his colleagues over Mr Martin's future. He said: "The central question is the authority of the Speaker and I'm not sure he has any authority at the moment.

"If he does not have any authority, there is no point in him carrying on." Mr Bacon will seek a meeting today with the Speaker to demand an explanation over why officers were able to search Mr Green's Commons office.

He was also planning to distribute copies of an article he has written over the furore which he predicts may result in a "string of resignations". Mr Bacon, who sits on the public accounts committee, suggested that Commons Clerk Michael Jack may also be forced to quit and that Home Office's permanent secretary Sir David Normington was in the "line of fire".

Gordon Brown stopped short of ordering an inquiry, saying: "There is going to be a time when all these things are going to be investigated and reviewed after the police have finished their work."

Mr Cameron and Nick Clegg stepped up pressure on the Speaker by demanding that he hold a meeting with the Tories and Liberal Democrats.

"I have a sinking feeling that the Speaker has let us down in something of incalculable importance and that it is now hard to see what he is there for," Mr Bacon added. "A parliamentary colleague has been arrested for doing his job. Making this right and protecting our Parliament transcends everything else.