MP John Baron has left his post as a shadow junior health minister after five years following David Cameron's shake-up.

He temporarily resigned from the role in early 2003 over his party's backing of the Iraq war, but was reinstated later that year.

Mr Baron has now been appointed an opposition whip, responsible for making sure there are enough MPs to vote in Parliament.

The announcement came as Mr Baron challenged Prime Minister Gordon Brown to release the first full draft of the Iraq weapons dossier during yesterday's Prime Minister's Questions.

He said: "The Prime Minister has talked much about the need for openness and transparency in politics. Can he therefore explain why his Government continues to defy the Information Commissioner by refusing to publish the first full draft of September 2002?

"Does the Prime Minister not believe actions speak louder than words?"

Mr Brown said it was going through the correct channels.

But Mr Baron added: "The Prime Minister says he wants less spin and more substance in politics. Yet here the Government is concealing an important document which may help to throw further light on the role spin doctors played in the run-up to the Iraq war."