Cabinet secretary Sir Richard Wilson has won guarantees from Downing Street that new legislation to restrict the role of special advisers will be introduced.

In the wake of the Martin Sixsmith/Jo Moore row, the proposals could now be included in this autumn's Queen's Speech.

"We are ready to bite the bullet. We know we are going to have to go further," one senior government figure told the Times.

Sir Richard will make a speech next week setting out the principles he believes should be included in the new Civil Service Bill, with limits on the numbers of special advisers thought likely.

As the Conservative Party backed similar measures, the Committee on Standards in Public Life is today announcing its consultation on the relationship between ministers, special advisers and civil servants.

With Sir Richard due to step down in July, the speech is being seen as a parting shot on Labour's "politicisation" of the civil service.

The Times reports that Sir David Omand is the surprise front runner to take Whitehall's top job.