But by and large, we just assume data protection is there, solid and useful in an age when every supermarket wants to know where you live and what shape you like your pasta. We suspect companies of selling on our addresses to junk mailers, but when it comes to government bodies we are sweetly trusting. Having nothing to hide, we fill in official forms on the blithe assumption that civil servants will use the information for dull necessities only. We do not fear that getting a passport will cause us to be bombarded with cold calls from double-glazers, that the police will flog our details to sofa salesmen or that the act of taxing the car will allow the Driver and Vehicle Licensing Agency (DVLA) to feather its nest by selling our home address to people with criminal convictions for extortion and blackmail.

But oops — they are. In that last case, it’s true. The inquiries of Norman Baker MP, after complaints by constituents and an investigation by The Mail on Sunday, reveal a DVLA practice that takes the breath away. Even the Department for Constitutional Affairs, when consulted, told the newspaper that it was illegal.

What is happening is this: requests come in from businesses that have relevance to parking — clampers, car park managers, even a financial services company that happens to have a car park in which, notionally, people might leave their cars without permission. The DVLA charges a few thousand pounds for a link to its database, and thereafter the commercial company has only to tap in any registration number to be sent the owner’s name and address. If crooked, it could collect car numbers from anywhere in the country, enter them and thereafter know when you are away from home. Or it could send you threatening letters, of extortion or blackmail, citing your car details and claiming a violation.

But the DVLA wouldn’t deal with such people, would it? Yep. It does. It has been forced to hand over its list of the 157 companies registered to buy personal information about drivers — the list includes bailiffs, debt collection agencies and financial services companies. DVLA bleats that it is obliged — under an undebated Statutory Instrument of 2002 — to sell the information to anyone with “reasonable cause”. Well, almost anyone can claim that a car might park in their space. Thus a credit company, which bombards us all with mailshots offering loans, is on the list because it’s got a company car park. Nor does DVLA check that it is not selling the list to people with criminal records: it deals with Aquarius Security — clampers whose management were found guilty of blackmail at Bristol Crown Court and given prison sentences. One of them was already on an ASBO after being accused of driving his truck into a 60-year-old man, breaking his knee. They clamped one young woman’s car in the middle of a three-point turn. But the DVLA saw nothing wrong in selling that company addresses for £2.50 each so that they could find other citizens to harass.

Other people who can get your address just by noting down your registration number include a car park management company, which without issuing tickets or reproofs sends bills for £170 to people it has secretly photographed overstaying the free limit in supermarket car parks, and another which notoriously forced an Olympic athlete to pay £335 to retrieve a clamped car in Swindon.

This may well be in breach of the Human Rights Act, but it certainly drives a coach and horses through the spirit of the Data Protection Act. Norman Baker said it was “outrageous”. Shami Chakrabarti, director of Liberty, considers it “extremely troubling”. The Information Commissioner’s Office is said to be “taking it up with the DVLA”, which I suppose could lead to the amusing situation of the commissioner issuing an enforcement notice against Alistair Darling, the Secretary of State for Transport.

I say “amusing” because in these dark times one must find fun where one may. But what is less amusing is that this piece of roughshod arrogance, done in the interests of tackling only the moderate nuisance of bad parking, throws a lurid light on what could happen to our privacy if we get ID cards to boost the “war on terror”. So far I have been lukewarm on the issue, only doubting that the cards would be good value (every atrocity so far has been committed by people whose papers were in order). But now I am not lukewarm. I am almost prepared to join Simon Hughes, the fiery Lib Dem, who has just pledged to go to prison over the issue. Given the casual attitude of the DVLA, willing to turn a penny by selling our addresses to any old crook, what would happen with information-rich ID cards and bureaucrats of similar calibre?

But if you would rather return to the amusing side of all this, note that the company that sets bailiffs on people who won’t cough up £170 for parking ten minutes more than a supermarket’s limit does value privacy: its own. When a consumer website tried to contact its nominee directors via an obscure shell company (a system that becomes illegal in 2007) it found an accommodation address and a man who primly said: “We wish to protect the identity and security of the senior administration of this company.” Meanwhile your security and mine are up for sale, government surplus, £2.50 a pop. You have to laugh.

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