But it is one more step in a world where growing numbers of agencies from private companies to central and local government hold ever-increasing amounts of computerised and cross-referrable information about individuals, their present and past lives and their lifestyles.
One of the biggest sets of information - though one of the best protected - is the decennial census, providing a mass of information on the 58 million people in the United Kingdom. It is broken down only to ward level, however - data on individuals is not disclosed. The Inland Revenue holds details of the declared income and taxation of all earners - but again under legal confidentiality restrictions.
Anyone who has worked has a national insurance number, with social security computers recording contributions and claims, details of employers, periods of unemployment, and receipt of benefits.
The police hold details of convictions and cautions, and in some cases, such as sexual incidents, information where the defendant was acquitted or charges dropped.
Criminal intelligence holds information on associates of people targeted by the police while MI5 and MI6 have files on suspects ranging from IRA bombers to foreign terrorists and members of groups judged at times subversive - the Campaign for Nuclear Disarmament, for example.
GPs and hospitals hold medical records which - subject to a dispute over patient confidentiality between the British Medical Association and the National Health Service Executive - will soon be available on the NHS computer network. Hospitals and health authorities will definitely use them and GPs are being invited to join.
The Driver and Vehicle Licensing Agency (DVLA) knows your car ownership, while BT and other telephone companies know which numbers have been called from your phone, when and for how long. Local government holds your council tax record and details of contacts with social services.
But the biggest change in recent years has been the growth of commercially held information on an individual's lifestyle and spending patterns - data built up by banks, mortgage providers and credit-card companies, supermarkets and magazine subscription lists.
Credit-rating companies can tell a prospective lender your last recorded address, anyone you live with over 18, whether you are bankrupt or have county court judgments against you as well as whether you are paying your present debts on time.
One boom area has been "lifestyle" surveys - one firm recently sending out 3 million qu- estionnaires asking people to answer 300 questions. The information is then sold for direct mail. Consumer "loyalty" cards are also booming, allowing shops to build up pictures of their customers' purchasing habits. Tesco, for example, has a database of 8 million names, 6.5m of them regular customers, which, with a few questions, allows them to target pr- omotions for the right market.
The Data Protection Act requires that computerised information solicited for one purpose must not be used for another without permission, but John Would, the Data Protection Registrar's director of operations, said: "I think people would be surprised at the level of information being held on them ... It is a continual concern that people's personal privacy is being invaded."
Liz Parratt, campaigns coordinator for the civil rights group Liberty said: "We are drifting towards a surveillance society because people don't pay sufficient attention to their rights and liberties."
Greg Bradford, managing director of CACI, which provides targeted marketing data to companies, says much more information about individuals could be assembled if everyone had an identity number that was freely available. Vast quantities of could be merged. But he said that with the legal restrictions on what can be disclosed, he did not believe it would be "commercially attractive for anyone to try it".
"People might find that idea of commercial data being merged frightening," he said.
'But for me the much bigger fear would be if government used the ID number to merge all the data it holds on us - that would be Big Brother."Reuse content