History often forgets the little people in life. One name, however, should not be forgotten. Just over 50 years ago a middle-aged dry cleaner from north London called Clarence Willcock changed this country by a simple action: he said no.

Willcock had been stopped by a policeman while driving home and ordered to show his ID card, which all UK citizens were required to carry at all times.

He refused, and thus began a year-long court battle over the right to be a free Briton without having to prove it at the drop of a hat.

As Tony Blair's conference speech this week has shown, ID cards are now back on the agenda.

Pushing them are those members of the Cabinet who want to curb asylum and terrorist incursions, IT companies that sense a billion-dollar boondoggle, and elements of the civil service who would like nothing better than to see everyone registered for yet more lovely paperwork.

But as any security professional knows, single-point security is useless.

You don't just wrap a server in a firewall and assume you're safe. Defence in depth is the watchword of the true security professional. You back it up with password protection, intrusion detection and virus monitoring. You make the system as safe as possible while acknowledging that even this may not be enough.

There is no such thing as a foolproof security system, and I'll make a prediction: within a year of an ID card coming into circulation you'll be able to buy one on the black market. Another five years and the encryption will be broken. What then? Will we all have to get an upgrade?

If the plans go ahead we will have the option of carrying an ID card just as computer users today have the option of using Microsoft's products: yes, you can do without, but it costs a lot of time and complicates matters immeasurably.

Companies, too, will be encouraged to build the ID card into business practices. I'd advise against it. But if you must, don't make it the sole point of trust; insist also on bank records, credit histories and all the other paperwork that fills modern life. It's a far safer way of doing business.