Taxi drivers used to be rather polite when they picked up a peer of the realm wanting a ride to the House of Lords. Now, one long-standing member of the Upper Chamber recounts ruefully: “They say - what's your rate?”

The normally genteel atmosphere of the Lords - this is a place where tea and crumpets are served every day at 4, and people still suggest meeting for a drink at the “Martini hour” - has been shaken to its 13th-century foundations by the cash-for-influence affair.

In the Pugin-wallpaper-lined dining rooms there is genuine shock about the allegations that four Labour peers were willing to take money to try to change policy. “It's so shaming,” says one frontbencher. “Wherever you go there are small groups of peers rather ashen-faced saying - ‘How could this have happened?'.” Lords Snape, Truscott, Taylor and Moonie have already been nicknamed the Harry Potter Four by their colleagues.

The tacky, materialistic and self-promoting behaviour of which they are accused is, of course, precisely the opposite of the values that the Lords should promote. The Upper House should be about public service, not personal enrichment. Whatever the outcome of the current investigation (and the peers deny the allegations) there must now be new controls on lobbying, as well as changes to the rules to ensure that convicted criminals can no longer sit in the Lords. Those who want to vote on the law of the land should also, of course, be obliged to pay tax in this country.

But there is a danger of learning the wrong lessons from this incident and of losing sight of what is good about the Upper Chamber.

When I first became a lobby correspondent 13 years ago, I covered the Lords and I have watched it closely ever since. Certainly there are eccentricities to the place - though the appropriately named Lady Strange, who used to predict the future by reading tea leaves, has died.

The cult of youth has yet to take hold in a House where the average age is 69. The film-maker Lord Puttnam once told me he could not understand why so many peers had hair that stood on end until he realised that it was the effect of static from the speakers positioned in the backs of the red benches to help members who are a little deaf.

But there is a wisdom generated by collective experience that often makes peers seem more in touch with public opinion than the elected representatives in the Commons. It was, of course, the Lords that rejected the Government's proposal to detain terror suspects without charge for 42 days - and knocked back plans to curtail jury trials, and imposed a limit on supercasinos. In the 1980s peers spoke for the people when they voted down Margaret Thatcher's plans to liberalise the Sunday trading laws.

There is an independence of spirit on the red benches that does not exist on the green ones. Although the whips send out a list of instructions (by e-mail - peers have been issued with BlackBerrys) these are taken as guidance rather than fact. This is partly to do with the make up of the chamber - Labour has only 29 per cent of the votes in the Lords compared with 54 per cent in the Commons, and the independent crossbenchers hold the balance of power with 28 per cent. If the Government wants to win a division in the Upper Chamber, it must first win the argument.

Perhaps as a result, the debates in the Lords are usually of a far higher quality than those in the Commons. There is an emphasis on making intelligent points rather than on point-scoring - exactly the sort of “new politics” all the party leaders claim to want but never deploy. When five former defence chiefs spoke out against the Government's treatment of the Armed Forces last year their intervention was so powerful because it was driven by experience rather than politics.

On any subject, the Lords has someone who knows what he or she is talking about. There is Lord Winston to advise on medical matters, Lord Bragg to give his views on broadcasting, Lord Browne of Madingley (the former head of BP) to discuss climate change - and a clutch of former law lords and Home Secretaries to give an opinion on legal questions. The recent debates on the economy have been particularly well informed. Indeed, many of the ministers most influential in dealing with the recession are peers, elevated to the Lords as part of Gordon Brown's Government of All the Talents - and it is good that their

knowledge of the City is being deployed in the national interest. By definition the non-ministerial outside experts have other interests - that does not mean they are sleazy.

The point about the Harry Potter Four is that they were all rather second-rate elected politicians (two former MPs, a former MEP and an ex-council leader) two of whom had been bumped up to the Lords to make way for ambitious younger blood - in the case of Lewis Moonie, in fact, to create a seat, after constituency boundary changes, for Mr Brown. They should never have been in the Upper Chamber in the first place. Some peers protest privately that they have “infected” the Lords with the values of the Commons.

It is fashionable to use the recent allegations to make the case for an elected House of Lords. But this would be yet another step down the road of creating a professional political class - precisely the thing the voters detest. There is a danger of ending up with an Upper House stuffed full of B-division apparatchiks who had failed to get a seat in the lower one. It is, after all, the professional politicians, rather than the Lords amateurs, who have caused all the recent problems.

I would prefer to see a house of appointed experts - some retired, some not - who could serve a fixed term. There is an appealing logic to the argument for an elected senate but, if enacted, the idea would turn out to be deeply flawed. Be careful what you wish for lest it come true.

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