Large-scale snooping is about to get up close and really personal, with radio tags in everything from bus tickets to new knickers. Big Brother will have his beady eye on our affairs as never before, if we allow it, and a simple trip to the supermarket could reveal far more about us than we’d ever imagined — even after we leave the store.

Radio Frequency Identification (RFID) is the “next big thing” in tracking technology for everyday consumer goods, and was recently rubber-stamped when Ofcom, the communications regulator, removed the need to buy a licence to run RFID systems. They have been trialled at M&S and Tesco, and are already built into London commuters’ Oyster travel cards. Research indicates that, within two years, the industry will be worth more than £3bn annually in Europe.

RFID works in a similar fashion to bar codes, but without needing physical or line-of-sight contact. A tiny transmitter, placed on packing or embedded in the product, sends signals to a reader, which transfers that information to a database. This, for example, could then request another case of Rich Tea biscuits to be sent from warehouse to shelf.

For retailers, the possibilities are clearly endless: from checkouts that scan an entire trolley at once to smoother supply chains and in-store marketing that second-guesses which gutsy red wine you might want with that lamb cutlet, or which shoes match the jeans in your basket.

Monitoring plonk and pants is only the start. People will be next. The government’s proposed ID cards look likely to include RFID, and trials are under way for car number-plate chips with a 300ft range — ideal for congestion charging. No wonder Ofcom and the DTI have encouraged industry: let the commercial sector familiarise the public with the touchy subject of radio tagging, which many civil-liberty campaigners believe is an invasion of privacy.

It’s easy to take an Orwellian stance on these snooping devices, but radio tags can be undeniably beneficial, too. According to the World Health Organisation, as many as 1 in 10 of all pharmaceuticals is counterfeit, and because radio tags are far harder to forge than bar codes, they could help curb this illicit trade.

Accurate tracking of medications is also cited as a way of reducing dispensing errors, which can only be a bonus: the Social Market Foundation says that more than 10% of UK hospital admissions are the result of medication errors. It’s also hard to argue against a technology that has triggered alarms and prevented tagged babies being snatched from hospital.

The real opposition is against tags being placed in everyday goods that we carry to the till and take home. These are not critical medicines or official documents, but our personal shopping, from the mundane to the mildly embarrassing.

If tags are embedded in the product itself — clothes, toothpaste — they remain there when you leave the shop and thereby pose what campaigners such as Consumers Against Supermarket Privacy Invasion and Numbering (www.spychips.com) see as an unacceptable threat to privacy. Third parties could track and discover an individual’s tastes and habits.

Although retailers have to comply with the Data Protection Act, hackers have developed ways to boost a scanner’s detection range to identify the tags in your handbag or house.

The technology to combine the valuable aspects of RFID with improved privacy already exists, but tags that can be disabled, or “killed”, at the checkout — thus protecting our personal data — inevitably cost far more than the simple models that industry is testing. Guess which version will probably win out.

Radio tags have a promising place in society, but it’s not in our shopping bags or underwear. If retailers want to turn us into walking inventories while we are in their shops, they might at least have the decency to turn off their electronic snooper when we leave their premises. Now is the time to stand up for our right to privacy, before Big Brother has moved into the home.

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