It's been a big week for databases, although nobody has managed to make them sexy. On Monday, the pressure group Liberty underlined the failings of the Criminal Records Bureau – more precisely its enhanced check – for the Today programme. It was quite a story: a woman had been turned down for voluntary work, having been "spoken to" (as opposed to "reprimanded" or "warned") by police for leaving her children in the park while she went to the shops. It's one of those stories you can imagine Basil Fawlty popping an eyeball over. And then you think, hang on – I'm popping an eyeball. This is outrageous. She only went to the shops.

This evening Damian Green, the shadow immigration minister, gave a speech to the Centre for Policy Studies, asking if Britain is a free country. He identifies 28 agencies that hold personal data about individuals. In the light of his very credible starting position – that politicians have a duty to create an environment in which "the citizen has some personal space in which the state has no power, interest, or influence" – many of these agencies and their purview do seem … well, bogus is a strong word. Let's start with "a bit much".

The Tories have seized this ground – they are tighter with Liberty than is Labour; and there is no telling whose manifesto will promise the most in terms of individual privacy.

It's not a bad time, therefore, to look at database management as practised by the Criminal Records Bureau, which is as uncontroversial and hi-tech as any similar initiative of the past three terms of government. It is also a massive undertaking – the 1.5m people checked in 2002 had gone up to 4m in 2008-09.

Now, this park lady (who wishes to remain anonymous) was the victim of the enhanced criminal records check – the standard check, everybody agrees, is almost totally unproblematic. It passes on only current and spent convictions, cautions, reprimands, and warnings – which proceed from an admission of guilt (to be cautioned you have to accept a caution). A standard CRB check can also access List 99, a register of people who have been barred from working with children – but basically this check is not open to tittle-tattle. Furthermore, and I believe more important, the CRB is on target to process 95% of its standard-check applicants within 10 days.

The enhanced check, conversely, has come to the attention of Liberty – and not just on behalf of the park lady – because it can include, above and beyond that raft of convictions and warnings, "relevant and proportional information held on that individual", as decided by the chief officer of police. This really could be anything. People are warned when they put in for an enhanced check that it could even flag up other people living at their address.

As another for-instance (if you are of a mind that one shouldn't go to the shops while one's children are in the park), say you have a very loud argument with your partner, and a neighbour calls the police: this information will be logged even if you personally don't make a complaint, and rightly so, because the police are thereby alerted to respond maybe fractionally faster if you were to make a 999 call.

But say this isn't domestic violence, and it's just a very loud argument – it will still end up on your CRB check. This has now entered the realm of gossip: it will be passed on to a prospective employer with no warning to you. When you do find out, you have no right to get it struck from your record; and if your application was for a job in a domestic violence refuge, for instance, you might well find yourself considered unsuitable to work there.

Worse to my mind, however, is the sheer bureaucracy of the enhanced check – the bureau has targets of 90% of applications being processed within 28 days. That sounds good, but it is missed in 10% of cases. And in the Metropolitan police area applicants are quoted six to eight weeks. Moreover you have to re-apply every time you change jobs; or every three years, and after maternity leave, if you stay in the same job. In summer the system is slower because teachers are all being vetted.

This is no victimless matter – people in these "caring professions" are left without income, or even the means to bring in a temporary income, for weeks at a time. Bear in mind that working with children or vulnerable people is rarely well paid in the first place, and you have a system with unjust financial penalties built into the very bureaucracy.

The gossip element will, I believe, be ironed out in time, especially as a new vetting and barring process will be introduced in October that should in the long run obviate the enhanced check. But the way people are treated by government agencies – this high-handed, "well, we do most of you in a month, what are you complaining about?" attitude – is astonishing to people who work outside these altruistic sectors. The Conservatives might have a much bigger vote-winner with their anti-surveillance crusade than it initially appears.