Derek Conway's behaviour was bad enough, but the Tory MP's excuse for spending nearly £400,000 of taxpayers' money on his wife and two sons was simply inexcusable. He blamed the scandal on “administrative shortcomings”.

What a very British excuse. By citing an unspecified organisational failure it manages to imply that someone else, deep in the machinery of Mr Conway's parliamentary office, is really the guilty party. By hinting at a paperwork snafu, it subtly recruits our sympathy, for we all hate bureaucracy. As an excuse, it manages to be simultaneously vague, slightly pompous and entirely meaningless.

So far from excusing Mr Conway, the very slipperiness of his excuse makes him seem that much more guilty, for as Shakespeare wrote: “Oftentimes excusing of a fault/ Doth make the fault the worse by the excuse.”

This week a small army of lame excuses have limped into the news, one after the other. Woolworths said it had named a girl's bed the “Lolita” without knowing what that implied. David Beckham's agent said he had failed to turn up at a charity event on Thursday because he needed to be in LA for fitness tests, and not just because he was in a tremendous snit after being dropped from the England team.

Increasingly, we have come to expect, and accept, excuses as part of the culture, not just in politics, but in business, sport, education and justice. The British not only produce the most inventive excuses in the world, we also have a bizarre tendency to accept them, whether or not we believe them.

As The Times reported this week, thousands of offenders who fail to turn up for community punishments have been getting away with providing their own sick note, or the excuse that they overslept. There is little suggestion that the probation officers in question really believed these people were ill or sleepy: they just needed to hear an excuse, any excuse.

The culture of self-exculpation is endemic, as if merely the act of offering an explanation, whether or not it is credible, removes any need to apportion blame. Train drivers are obliged to offer excuses, however hollow, for every delay. Excuses for railway failures have attained the status of myth: the familiar “leaves on the line” and “the wrong sort of snow” have been supplemented, over the years, by the wrong sort of pollen, pigeon droppings in the signal box, too much sun, and the delightfully seasonal “an outbreak of buddleia”.

One rail manager demonstrated an impressive ability to elaborate on an old theme last year by insisting that the leaves on the line “are bigger and juicier than we have seen before”.

When businesses issue profit warnings, these tend to come hedged around with thickets of excuses: the war, the lottery, El Niño, the World Cup, the weather. Several excuses are always less convincing than one, but companies are happy to cite any number of extraneous factors so long as this diverts attention from their own failings. Lord Kirkham, founder of the dfs furniture group, still holds the record for most excuses packed into a single explanation, when he had to reveal the company's first profit fall in 28 years in 1998: these included the “Diana effect” (everyone was too upset to think about buying a sofa), the summer heat, Easter flooding, high interest rates and an early tax deadline.

The British instinct to reach for an excuse, no matter how flimsy, is partly politeness. A Frenchman feels no qualms in turning down an invitation without explanation, but an Englishman feels obliged to offer a reason. Only occasionally does the truth show through. Lord Charles Beresford was once summoned to a dinner by the Prince of Wales, later Edward VII, and replied by telegram: “Very sorry can't come. Lie follows by post.”

A survey by Andrews Salts, the morning-after remedy, recently found that people seldom cite a real reason, such as a hangover, for absenteeism, but prefer an elaborate excuse, or several. The survey included my all-time favourite plea for not turning up to work, so strange it can only be true: “I mistook a tulip bulb for an onion.”

British schoolchildren apparently offer more extravagant excuses for failing to do their homework than any other country in Europe. “The dog ate my homework” does not exist as a phrase, let alone a cliché, in any other language. We treasure the more impossible excuses, delighting in their inappropriateness (“Sorry,” said Alan Clark, once the police had finally caught up with his speeding car. “I thought you were giving me a police escort.”)

It is one thing to deny the truth, but a peculiarly British affliction to feel the need to offer an alternative version of reality that is not quite a lie, but is rather less than the whole truth. The British reaction, when caught in the act or when something goes wrong, is to wriggle and justify: We wuz robbed, I was badger-spotting, my wardrobe malfunctioned, it was market forces, the ref is blind, I was merely comforting her.

Rudyard Kipling once wrote: “We have forty million reasons for failure, but not a single excuse.” Today, that equation might be reversed: the real reason for any kind of failure is buried under millions of excuses.

It may be human nature - it is certainly British nature - to hide responsibility behind vague pretexts, unforeseen circumstances and administrative errors. But once in a while, how refreshing it would be to hear a different approach from the politician, the football manager and the train announcer: It's a fair cop, the pitch was fine, the rail system is rubbish, the cheque is not in the post, business is terrible, it's all my fault, and there is no excuse.

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