His threat of what amounts to civil disobedience against the House of Commons came as the Speaker, Betty Boothroyd, announced she had ordered a formal investigation into how the Guardian sent a fax bearing a Commons crest to the Paris Ritz while pursuing its inquiries into Jonathan Aitken's stay at the hotel.
Mr Benn's announcement, which provoked gasps of astonishment and anger from Tory MPs yesterday, will raise the stakes in the debate over whether the committee should be meeting in private after MPs last night defeated by 301 to 264 votes a Labour motion explicitly calling for the hearings to be in public.
With the Guardian incurring cross-party criticism over its use of a Commons crest on its request for a copy of Mr Aitken's bill, the Speaker revealed to MPs that she had asked the Serjeant at Arms, Sir Alan Urwick, to carry out an inquiry and report back to her.
Moves against the Guardian helped provide some respite for Mr Aitken, Chief Secretary to the Treasury, after a fresh attack by Mohamed al-Fayed, owner of Harrods, who yesterday again challenged Mr Aitken's account that his wife had originally paid his hotel bill. Mr Fayed said a cashier at the Ritz told him that he was certain the bill had been paid by the secretary of a Saudi Arabian businessman and friend of Mr Aitken.
The Speaker said Sir Alan, who interviewed Peter Preston, the editor of the Guardian, yesterday, would ``investigate all the circumstances so that I can decide what further action it would be appropriate to take''. She said that she took ``account of the Guardian's misuse of House of Commons writing paper . . . very seriously indeed''. More than 100 Tory MPs last night signed an Early Day Motion calling for Mr Preston's dismissal and for his case to be referred to the Director of Public Prosecutions.
The Speaker's announcement came at the start of a vintage debate that went to the heart of the issue of whether the Commons was fit to regulate itself by traditional methods, and in which Sir Edward Heath appealed to the Privileges Committee to reconsider its three-century-old practice of holding private hearings.
Labour MPs on the committee are expected to attend today's session of the committee before deciding whether to continue the boycott they announced two weeks ago.
Mr Benn, the senior member of the committee, cited the 19th-century defiance of the Commons by William Cobbett and Thomas Hansard in reporting parliamentary proceedings before it became legal in 1855: ``I am no longer prepared to accept the present restrictions, and if I attend future meetings of the committee, it is my intention to issue my own personal report of the proceedings which I attend.'' Mr Benn, who intends to type reports each day based on short notes of the main events of each session, cannot be directly expelled by the members of the committee, which today continues its inquiry into the ``cash for parliamentary questions'' allegations made against two backbenchers, Graham Riddick and David Tredinnick. Instead, the committee would have to recommend to the House that Mr Benn should be thrown off the committee.
Tony Newton, the Leader of the Commons, rejected in the debate what he termed a ``half-way house'' of part-public, part-private hearings, as suggested by the Labour motion. ``There is no evidence that such an arrangement could be made to work,'' he said. It would not be thought fair to hear some witnesses in private and some in public, and he doubted the committee could judge in advance whether issues were going to arise that should be heard privately.
John Prescott, Labour's deputy leader, told MPs: ``The public will assume that we have something to hide if we continue to investigate these matters in private.
``We need to display to our constituents the simple truth - that we are here to serve them before we serve ourselves, and that is best done by being open and by holding these investigations in public.''
One Tory defied a three-line government whip and voted with Labour: Richard Shepherd, MP for Aldridge Brownhills, a long-standing freedom of information campaigner.
Unanswered questions, page 3
Andrew Marr, page 17