Last week's decision by the UK cabinet to delay legislation on the introduction of a national ID card was made largely on the grounds of cost and doubts about the technology, but in a useful roundup of who's for and who's against, and why, today's Guardian reports that some "principled opposition" also exists.

Unhelpfully, the paper doesn't exactly name names for the principled opposition, but the pre-Blair CVs of Peter Hain, Patricia Hewitt and Charles Clarke, which it names as objectors, leads us to believe that they may be among the culprits. John Prescott is also said to have "reservations."

Principle, however, did not need to come into it at last week's meeting. Chancellor Gordon Brown is reported as unenthusiastic, but prepared to let the scheme go ahead provided the Treasury does not have to pay. This agnosticism however opens the door to a 'national ID card by stealth' approach, where the individual departments benefiting from ID cards contribute to the cost. The home office has already begun introducing biometric ID cards for asylum seekers, and biometrics on passports and driving licences are coming. Add in support from work and pensions secretary Andrew Smith, who sees cards as a weapon against illegal working and benefit fraud, and health secretary John Reid, who wants to block "health tourism" on the National Health Service, and there's the potential to mop up virtually all of the population.

And actually, although the introduction of a compulsory national ID card would have a massive symbolic effect, that is really not the issue; nor, in the end, is cost. ID records in all of the concerned departments already exist, and we're grateful to the several teachers who, in response to our report on the government's Every Child Matters Green Paper, pointed out that UK schoolchildren already have a unique ID in the shape of the Unique Pupil Number (UPN).

All of these records and more will increasingly be dealt with by electronic means, resulting in electronic versions of a whole series of ID records they've already got on you. Add in the probability of increasing interoperability and increased sharing of data across departments, and you end up with what is effectively a national ID record anyway. In that sense, the most significant aspect of Every Child Matters is its intention to "remove legislative barriers to better information sharing, and the technical barriers to electronic information sharing."

Similar barriers are likely to be removed in other areas in order to fight terrorism, illegal immigration, benefit fraud, health tourism [fill in populist issue of your choice here], and more general joined-up ID will result, controlled only if sufficient "principled opposition" spots that it's happening.

In favouring eye-scanning or fingerprinting the entire population, Home Secretary David Blunkett is therefore arguably barking up the wrong tree. He's getting what he really wants in the shape of joined up records and cross-departmental snooping, but he's busily wasting his time lobbying for what he thinks he wants. Sure, at various points it will be helpful/necessary to accurately link an individual to a record, but as has has been pointed out here, dabs ain't necessarily the most effective way to do this.

So we've got John Prescott's domestic affairs committee looking into the technical side of biometrics, and in the event of the committee concluding it's do-able, we've still got the prospect of the Great British Public's reaction to being charged £40 for the privilege of being compelled to go and have an eye-scan and/or get fingerprinted. It'll never play?

But we feel a conspiracy theory coming on. For as long as Parliament, the papers and the public argue about the side issue of whether you should have to carry a biometric ID card or not, joined up ID can continue its steady progress without anybody paying it much mind. And the unique national ID number is probably the next step.

Thought you had one of these already in the shape of your national health number? Well yes, you sort of do, but there is a commitment by a previous government that the national health number should not become a creeping ID number. According to the Department of Health's publication General Principles in the use of the NHS number, it "cannot be used by organisations that are not involved in the provision of patient care. This ruling covers other government departments, such as the Inland Revenue, Police or National Insurance as well as other commercial organisations..." So really, we should be watching for the removal of this, and other similar, "legislative barriers". ®