Mr Mitchell was appearing before the Standards and Privileges Committee after an allegation that he tried to subvert the inquiry into the Neil Hamilton cash-for-questions affair two years ago when he was a whip and a member of the now defunct Committee on Members' Interests.
Mr Mitchell told the committee: "Perceptions, as well as the reality, matter. I think it would be better if the House were to decide that whips should not sit on committees such as this one."
Then a whip, Mr Mitchell, had been appointed to the committee in June 1994, in a highly unusual move since whips did not normally sit on such committees. Mr Mitchell said he had not realised that whips had never served on such a committee and did "not appreciate" at the time of his appointment that the committee was a quasi-judicial one.
Mr Mitchell said he had acted "properly" throughout his membership of the Members' Interests committee. He said: "While I was a member I behaved entirely properly and with integrity both on and off the committee." Throughout the questioning, Mr Mitchell denied that he had revealed confidential discussions in the committee to anyone outside it.
This is the first time that an MP appearing before the committee has had to give evidence on oath. Dale Campbell-Savours, a Labour member of the committee, suggested that it was strange that Mr Mitchell had not appreciated the role of the potential judicial role of the members' interests committee since the Hamilton affair had first come to light in May 1994, a month before Mr Mitchell's appointment to the committee.
Mr Mitchell replied that Mr Campbell-Savours was speaking with the benefit of hindsight and that no one had objected to his appointment to the committee, including Mr Campbell-Savours: "Any of 651 members could have objected. No one objected," he said.
Mr Mitchell, who is the second minister to appear before the committee whose findings led to the resignation of the paymaster general, David Willetts, last month, is accused of passing on privileged information, obtained as a member of the committee, to Richard Ryder, the chief whip. He wrote a memo on 24 October 1994 to the chief whip, after he had seen the Registrar of Members' Interests, to ask him about the significance of an article in The Independent that day which suggested that Mr Hamilton had failed to declare an interest in consultant to the registrar.
Giving evidence, Mr Mitchell said he could not remember the circumstances in which the memorandum was written.
Mr Mitchell escaped much more lightly from the committee's probings than Mr Willetts. Quentin Davies, the Tory who famously savaged Mr Willetts, did express surprise that Mr Mitchell had underlined "in confidence" on the memo but afterwards only asked a few gentle questions in an effort to establish facts.