There is a marvellous irony about the fact that, last week, MPs discovered just how embarrassing it can be when private information reaches the public domain. First up was the home secretary, pale-faced and tight-lipped after the revelation that her husband had been renting pornographic films at our expense. Overnight, Jacqui Smith had lost dignity and everyone felt free to comment and jeer about the couple’s attractiveness, sex lives and the state of their marriage. The rest of her expense claims provided more material for outrage or mockery; whether she was claiming for an extremely expensive sink (£550) or an extremely cheap bath plug (88p), it was hard to avoid the impression of a senior politician milking the taxpayer in an unseemly and avaricious fashion and looking considerably diminished as a result.

Some MPs privately found her discomfort funny, but the next day the rest of the Commons was faced with the possibility that embarrassing claims of their own were about to surface. It turned out that the details of every MP’s expenses had been copied and leaked and were on sale to the media for an asking price of £300,000. The claims had been due to be published officially in the summer, but only after every member had had the chance to delete any details they wished to keep private. The bad news was that both the original and edited versions were now on sale, potentially allowing the rest of us to discover just what nervous MPs didn’t want us to know.

Parliament’s indignation at this breach of security would have been funny if it weren’t for the fact that these are the very people who have voted for massive state intrusion on, and information gathering about, the rest of us.

All along we have been assured that we needn’t worry about leaks and that the security of our information won’t be compromised. Last week we saw that the state can’t even guarantee the privacy of a few hundred lawmakers, let alone their 60m constituents.

The naivety of the Speaker’s reaction was petrifying. He told the Commons that he was deeply disappointed by the leaks. They should not have happened. The outside contractor that had processed the claims had been security vetted and had been employed “in good faith”.

Reassured? Me neither. But that naive approach is characteristic of the state’s approach to our data. It doesn’t understand that it is impossible to guarantee the security of the massive and comprehensive databases it is assembling on us. Files will be lost or hacked into but, above all, individuals will decide to snoop or leak. And that leaves us extremely vulnerable.

Our actions are about to be tracked and analysed from nursery to death. Forget the idea of growing out of your past; the state will never let you leave it behind. Schools will record not just your education, but also your family background and your behaviour. Fights in the playground, late attendance, trouble with your mother, an alcoholic father; it will all be there.

From next year, if social services think you need help, every detail of their value judgments about you and your family will be held online. All of this will be cross-referenced to ContactPoint, the child database, which will link to every other service a child might use, from drug advisers to psychiatrists to probation officers. No child can escape being listed on it and a third of a million people will be able to access it.

A middle-aged school governor and senior youth worker, who I know, is left reeling by this development. She says she would never have had her respectable career if the drugs, lies and stealing of her troubled teenage years had been recorded to haunt and possibly expose her.

Every potentially humiliating detail of our adult lives is going to be mapped, too. The National Health Service database will allow hundreds of thousands of people to view our medical records, with anything from abortions, depression, sexual diseases or long-term illness available to view. The new communications database, accessible to all police forces and 510 public bodies, will show that a judge watches porn websites, that a banker is researching suicide, or that a celebrity is continuously texting a woman who isn’t his wife. Meanwhile, the police want the right to hold all their records on us until we are 100 years old.

None of this information will be safe. Already ContactPoint is accidentally revealing the details of 55,000 vulnerable children, whose contacts are supposedly secret, every time the database is updated. At HM Revenue & Customs, more than 600 staff have been dismissed or disciplined in three years for snooping and one woman has been jailed for twice revealing the details of a battered woman’s whereabouts to her ex-husband. Local authority staff in 30 areas have been making unauthorised searches on the Department for Work and Pensions database, curious about the employment and income details of people they know. As the databases expand, the problem will only get worse.

If we do nothing about this expansion of state interference then we – like Smith – will have to live in the fear that at any time the gap between our public and private selves will be mortifyingly exposed.

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