Vincent Cable, your moment has come. Perhaps Dr Cable really does have no desire to be the next Speaker of the House of Commons. He may well be gambling on the slim possibility of a hung Parliament in which he may play the role of economic éminence grise from within government rather than without. He may even still have enough appetite for opposition to harry a new government on economic policy as he has harried the current one. Dr Cable may, in other words, have to be dragged to the Speaker's chair. His first words on the topic indicate that to be the case.

But being dragged is exactly what happens: when a new Speaker is elected the successful candidate is physically dragged to the chair by other MPs. Historically, if the monarch did not agree with the message being communicated then the early death of the Speaker could follow. Hence, previous Speakers required some gentle persuasion to accept the post. So might Dr Cable.

But there are good reasons why he would be the right man for the job. The saga of MPs' allowances has been a disaster for public life in Britain. That the vast majority of MPs have not even featured in the stories has done nothing to lessen the impression of a venal body politic, staffed entirely by functionaries who care more for lightbulbs than for ideas. It is, in all but a few egregious cases, an unfair impression but the public anger is genuine and the crisis in trust is very serious indeed. The next Speaker needs to be a man or woman of the highest integrity, one who has come through the current travails without a blemish to his or her name, and one who, in a sense, has managed to create a personal aura as somehow above the political fray.

The hidden story of Michael Martin, who beat Sir George Young to the job in 2000 as a result of a political campaign, is salutary. In defiance of the usual convention that the Speaker should come from the opposition benches, Mr Martin was placed in the Speaker's chair with the help of partisan, machine politics.

As a result, his command over the House was diminished from the start. That he turned out to be a poor Speaker, with a limited grasp of procedure and no ability to exert any authority in the chamber, simply confirmed the belief of his critics that he was in the exalted seat purely because of a political fix.

In these circumstances, it is crucial that partisan politics should be absent from the choice before the House. Liberal Democrats enjoy a detachment from the cut and thrust of parliamentary politics that they would not wish for. But, in addition, Dr Cable has managed, through the quiet authority that comes from his background as a professional economist and a courteous and reasonable manner in argument, to carve out a place for himself both as an economic prophet, which is slightly exaggerated, and as a man of great repute, which is not.

The trade of politics, which is more noble than not, has taken a fearsome battering recently. Sooner or later it will have to be repaired because the alternatives are worse. The job of Speaker suddenly comes with a mandate for serious reform. It now requires a Speaker who simultaneously commands both wide recognition and respect in the country. The right Speaker could become a genuine power in the land.

To participate in a debate in the Commons or at Question Time, MPs have to be called by the Speaker. MPs usually rise or half-rise from their seats in a bid to attract the attention of the chair. This is known as “catching the Speaker's eye”. There are certainly other good candidates, men of great distinction, such as Sir George Young and Frank Field. But, until he rules himself out, everything needs to be done to catch Dr Cable's eye.