Would you want this man as an enemy if your political career depended on his support?

Quentin Davies is a member of the Tory awkward squad. David Willetts, the Paymaster-General, was visibly shaken by his fierce grilling at the hands of Mr Davies in the hearings of the Committee of Standards and Privileges. He is also a member of the Treasury select committee and his questioning technique has certainly earned the admiration of fellow members there, one of whom, Labour MP Diane Abbott, described him as "like a ferret down a rathole".

Mr Davies is not a man to have as your enemy when your political career depends on his vote. He has shown, in voting against the whip on the vote on the Scott inquiry, that he is prepared to go all the way and clearly Mr Willetts's ministerial career is dependent on Mr Davies not repeating that rebellion by voting, with his Labour colleagues, to recommend to the House that Mr Davies should be suspended.

At Monday's hearing Mr Davies started off questioning Mr Willetts with a sort of "nothing personal, guv just doing my duty" explanation, but then launched into the type of cross-examination more associated with prosecution lawyers. Mr Davies not only called Mr Willetts's explanation "implausible" but made it clear, in the whole tone of his questioning, that he felt that Mr Willetts was a liar.

It is not the first time that Mr Davies, a merchant banker by trade, has given witnesses a hard time. On the Treasury Select Committee he made Eddie George, the governor of the Bank of England, very uncomfortable when the committee examined the collapse of Barings bank, again using the word "plausible".

Ms Abbott said: "Once he is convinced of a case intellectually, nothing will sway him from it." This explains why Mr Davies was the only Tory rebel on the vote on the Scott inquiry last February which was only won because fellow rebel Rupert Allason voted at the last minute to go into the Tory lobby.

According to Ms Abbot: "He is not from the salon des refuses like the other Tory rebels. He is doing it out of principle. He read every word of the Scott report, unlike most of his colleagues, and that's why he felt he couldn't vote for the Government on it."

Several of Mr Davies's friends in the House are bemused that he has not achieved ministerial office since he was elected for Stamford and Spalding in 1987 given that his ability and intelligence is easily on a par with that of the highly thought-of Mr Willetts. There are two possible explanations, his pro-European views which were expressed in a pamphlet written for the Macleod Group published this summer, and his rather patrician air. As one Tory backbencher put it, "He is all public school and la-di-da accents. That doesn't go down well in the grey world of Mr Major."

It seems that having seen many less able colleagues attain ministerial office before him, Mr Davies decided to show his spurs by being troublesome. He did this after Labour colleagues suggested that he needed to raise his profile, since he was getting nowhere by toeing the line.

A friend of Mr Davies's added: "He is a very honourable man. He is not doing this out of bitterness, but because he believes that Parliament should put the flag out for high standards. He feels that public perception of Parliament is at a low point and it is his duty to help ensure that this changes."