Leading article: The man who can speak no evil?

Many outside the Westminster village will be scratching their heads at the intensity of the row which has blown up over taxi expenses claimed by the Commons Speaker, Michael Martin, and his wife, Mary. Mrs Martin, the first Speaker's wife not to be allocated an official car, says that over four years she has spent about £20 a week on cabs, fetching food for official receptions. Mr Martin's official spokesman has quit over the affair. But if there is an irregularity here, it seems pretty minor.

Equally bewildering is the argument of those who defend Mr Martin on the grounds that the attacks are all a witch-hunt based on class snootiness and the broad Scottish accent of the man some Tory backbenchers refer to as "Gorbals Mick". If such attitudes exist, they were not deployed with the same ferocity against previous Speakers such as Betty Boothroyd, Bernard Weatherill or George Thomas – all from fairly humble origins.

Behind the scenes there are rumblings that Mr Martin has not been as incisive or non-partisan in the Speaker's chair as many MPs would have expected. There have also been reports about difficult relationships with key staff. But, again, it is all comparatively petty stuff which it would be possible to wave aside were it not for one thing. The Speaker is the man who is to preside over a root-and-branch reform of MPs' expenses and allowances, in the wake of the Derek Conway affair and various other incidents of parliamentaryvenality.

Mr Martin has certainly broken no rules in using air-miles clocked up on public business to subsidise a private family trip. Nor has he breached regulations in claiming £17,000 a year in allowances on a house on which he has already paid off the mortgage. But what all this does suggest is that Mr Martin is not the best person to preside over this review. The lax rules that govern MPs' expenses need to be tightened up and the elaborate allowances system simplified and policed a good deal more efficiently. But can Mr Martin be a credible wielder of the banner of reform? At a time when public trust in politicians is at a nadir, it would be a good idea for Mr Martin to step aside from this role.

Whether he should step aside as Speaker is a different matter. It would do Parliament no good for its most senior layman to be hounded from office. It would be far better if Mr Martin were to announce in a couple of months that, having served two terms in the job, he intends to stand down at the next election. On past precedent, he can expect a graceful transition to the House of Lords. With its ample allowances, and what is reputedly the best wine cellar in London, he should be very happy there.