By Ian Dunt
Downing Street took the remarkable step of refusing to field a Cabinet minister on last night's Question Time after it objected to the presence of Alastair Campbell on the panel.
The government insisted on the removal of Mr Campbell, former director of communications to Tony Blair, because he was not a member of the shadow Cabinet.
Bu the BBC refused to change guests at Downing Street's request as a matter of "fundamental principle".
Tory MP John Redwood, who has demonstrated his willingness to rebel against the Tory leadership this week with a letter to the Treasury on capital gains tax, appeared for the coalition government instead - although he was sourced privately.
Question Time executive editor Gavin Allen said it was the first time during his time in the job that Downing Street had made such a request.
"It is a fundamental principle of our independence that politicians cannot dictate who sits on the panel," he said.
"It is for Question Time, not political parties, to make judgements about impartiality and to determine who is invited to appear in the interests of the audience.
"Parties are free to accept or reject those invitations but they do not have a right of veto over other panellists. Licence fee payers rightly insist that the BBC must be free from political interference."
A Downing Street spokesman said: "In the week of the Queen's Speech the BBC booked Alastair Campbell in the place of an opposition front bencher to appear on Question Time - which we questioned.
"Before a final decision was made on who might appear on behalf of the government the BBC directly booked John Redwood MP."