The Cabinet minister facing questions

Cabinet Office minister Tom Watson was facing uncomfortable questions today over what he knew of the dirty tricks conspiracy.

Downing Street refused to deny that he was aware of the plan to set up the Red Rag website, where scurrilous stories smearing senior Tories were to be planted.

The failure to clarify Mr Watson's position left a question mark over his future. The MP was keeping a low profile today. He has not updated his blog since last Friday, when the story broke, and officials were unable to say whether he would attend a Digital Britain summit on Friday, even though he is the Minister for Digital Engagement.

Mr Watson was mentioned in one of the leaked emails and MPs were speculating that he would be exactly the sort of person the conspirators might have consulted about how to make their idea work.

The combative Brownite is based in the same open-plan office in Downing Street as Mr McBride. He is a fan of the internet, his Cabinet Office biography boasting: "Tom was Parliament's first blogger."

Mr Watson issued a statement at the weekend saying he had "no involvement" in the Red Rag plan.

Ironically, Mr Watson has been sacked from ministerial office once already for going over the top to help Mr Brown. Tony Blair fired him in 2006 after he was identified as a ringleader of the "Curry House plot" to force the then-premier to quit.

It emerged that Mr Watson had been to Gordon Brown's house in Scotland the day before a letter calling for a change of leader was posted.

But Mr Watson, a West Midlands MP, insisted he merely popped over to drop off a present for Mr Brown's new baby.