Dominic Lawson: It is not the corruption that galls – it is the sheer pettiness

These are the petty acts of spongeing by inconsequential people

Mrs Mranil Patel, a 41-year- old mother of three, faces the possibility of a year's imprisonment. She is the first person in Britain to have been charged with "school application fraud". Mrs Patel gave her mother's address as her own, when submitting an application for her five year old son to enter Pinner Park First School. Her mother's house was in the catchment areas for this popular school, whereas her own family home was three miles outside.

Mrs Patel, who insists that she was living with her mother at the time the application form was posted, will appear before Harrow magistrates later this month on a charge of "fraud by false representation."

It is the contrast between the treatment meted out by the state to "ordinary" people such as Mrs Patel and the apparent impunity of home-flipping Members of Parliament, which so outrages the public, and understandably so: "fraud by false representation" seems as good a phrase as any to describe some of the claims by MPs in slavering pursuit of the maximum allowances permitted by the parliamentary authorities.

The Commons' own Green Book, which sets out the rules for 'Honourable Members', states explicitly that "claims must only be made for expenditure necessary for a Member to incur to ensure that he or she could properly perform his or her parliamentary duties". Yet Oliver Letwin claimed for the expense of mending the pipes under his tennis court; John Gummer claimed for the cost of removing moles from under his lawn.

As it happens, my peace of mind had been disturbed by the emergence of molehills on the grass outside my study, and I paid someone to get rid of them; so yesterday I rang up my accountant and asked him what the Revenue would think if I claimed this cost back against the tax on my earnings as a freelance journalist. "They'd think you were taking the piss, " he said.

This is a fair summary of what such MPs have been doing; but the extraordinary thing is how accommodating the Commons "fees office" has been, in contrast to the way the Inland Revenue would undoubtedly respond if a small businessman tried the same sort of stunt. Thus it was that the taxpayers ultimately paid for the extermination of the moles under John Gummer's lawn.

Indulgent as these clerks have been in their interpretation of what counts as "necessary in the performance of parliamentary duties", it has still not been enough for many MPs. The Culture Secretary Andy Burnham fought a running battle with the Fees Office over a £16,500 claim for the refurbishment of a London flat, being rejected three times-- before his plea that a further delay in getting the money reimbursed might put him "in line for a divorce" apparently moved them to cough up £16,500 of our money.

Another Labour MP wrote to the Fees Office in November 2004: "I object to your decision not to reimburse me for the costs of purchasing a baby's cot for use in my London home. Perhaps you might write to me explaining where my son should sleep next time he visits me in London?" This is like the incapacity benefits racket, in which doctors sign forms which mark healthy people down as unable to work for medical reasons, simply because they no longer have the will to resist the aggression and even abuse they receive if they refuse.

It's been fascinating in recent days to see how MPs caught out in particularly egregious exploitation of the "additional allowance" have advanced two arguments. The first is that they had acted "within the rules". Recall, if you will, the fury with which MPs reacted to the insistence by the former board of Royal Bank of Scotland that the pension it had awarded to Sir Fred Goodwin was "in accordance with his contract". "What about right and wrong?" howled the very MPs who in their own interest have advanced exactly the line taken by the now dismissed board of RBS.

The second argument used by those singled out for exposure is a more subtle one: they say, with a pious expression, that the entire system stinks and that "The whole House of Commons must apologise". This is a clever way of trying the classic defence lawyer's argument that "we are all guilty"; the point being that if everyone is guilty, then the idea of any individual responsibility conveniently disappears.

Funnily enough, the system now universally denounced as unacceptable may not now need to be changed at all. Bear in mind that all these expenses, down to the smallest item, were going to be made public anyway, as a result of a High Court judgement which overrode the Commons' attempt to block a request under the Freedom of Information Act; yet at the time these expenses had been claimed, the MPs acted in the belief that none of this would ever be published. The Scottish Parliament some years ago voluntarily decided to make all its members' expenses public; this had a salutary effect on behaviour, ruling out the sort of excesses which took place in Westminster.

After all, there are two basic social mechanisms which make humans behave properly, when their baser instincts might otherwise lead them into wrongdoing. The first is conscience, sometimes described as a sense of guilt. Obviously, not every MP has a highly-developed conscience, although many do. The second social mechanism is shame: if someone fears that a certain action might render him the subject of public obloquy, he will be reluctant to carry it out.

That is what complete transparency on MPs' expenses has achieved in Scotland – and would achieve south of the border. Transparency is beneficial in another way: even if an MP cannot be shamed into propriety, if his electors know what he has done and disapprove, then they will cast their votes accordingly.

We should not fall into the fallacy of believing that this generation of MPs are uniquely corrupt. I have read articles saying that this would never have happened in Winston Churchill's day; but Churchill had been completely unscrupulous in mixing politics with his personal finances. For example in 1923, while out of power, he secretly accepted the then vast sum of £5,000 from Burmah Oil to argue its case for a merger with the Government-owned Anglo-Persian Oil Company (later to become BP). Churchill had meetings to discuss this deal with both the Admiralty and the Board of Trade, neither of whom knew he was being paid by Burmah Oil to act in its interests.

David Lloyd George is more commonly recognised to have been financially corrupt in his political dealings: indeed, entire laws were passed in order to make sure that no Prime Minister could ever again act as he had done. Yet Churchill and Lloyd George were great men, who are rightly both celebrated for their achievements, even by those who acknowledge that they had often behaved outrageously.

The most depressing aspect of the corruption of the present generation of politicians is that it is all so mean. A male MP claims cash for his wife's tampons; another seeks reimbursement for a 5p polythene bag; yet another claims for the cost of a Remembrance Day poppy wreath. It is for such piffling amounts that they are prepared to sell their honour.

These are the petty acts of spongeing by inconsequential people, who seem to have little better to do with their time than jot down every single item of household expenditure, down to an 88p bathplug, and then whine endlessly to the Commons clerks if each last trivial item is not reimbursed at the public's expense. It is worse than a scandal: it is pathetic.