Just how much privacy are we prepared to give up?

This should be a short blog, as it asks a simple question, prompted by the announcement that both Visa and Mastercard are looking to sell customer data to advertising companies. However, while the question is simple enough to ask, it is not so straightforward to answer.

While I don't have any firm statistics to back this up, I can't imagine that many people are so violently opposed to having their data stored anywhere, that they systematically erase their financial and spending trails as they go along - pay by cash or cheque, seldom give out an address, always check the "no marketing" box, avoid internet spending, use a bank account purely as a repository for money and not as a base for standing orders and direct debits, etcetera. If you're out there and reading this in an Internet cafe, please do come forward

The majority of us consumerist Westerners - I think - will have some 'form' in giving up some information about themselves to purveyors of financial services and consumer products. We mostly have a piece of plastic, indeed - as I found out to my chagrin a few years ago, when trying to pick up a rental car - some services won't accept anything else. And even if the situation isn't quite so binary ("no card, no siree") we are prepared to give up a piece of ourselves for the sake of lower cost, increased convenience or other benefits.

It's a trade - we accept payment for elements of our privacy. In the case of supermarket loyalty cards for example, we know that we and our shopping habits are being scrutinised, like "transient creatures that swarm and multiply in a drop of water." But, to our delight, we receive points, or vouchers, without really worrying whether we've got a decent return on our investment. I do, occasionally, buy something completely random that I don't need, just to throw them off the scent.

It's the same for online shopping. However clunky the algorithms appear to be - just why do we still receive books for nine-year-old girls, some six years later? - be in no doubt that every purchase is being logged, filed and catalogued. It seems such a small step, when you buy a paperback from Amazon rather than paying in cash for the same book from the local shop; the difference, however, is that the purchase of one will remain forever, indelibly associated with your name.

There was a certain gentleperson's agreement that was in place at the outset, given that nobody ever reads the T's and C's of these things. Namely: that the data would only be used for the purpose it was originally intended. Indeed, such principles are enshrined in laws such as the UK Data Protection Act (DPA). But purposes change, and so do businesses, and it isn't all that easy to map original intentions against new possibilities.

Enter online advertising, itself subject to regulation in various forms including the DPA. It is unlikely that the Web would exist in its current form without the monies derived from advertising, from click-throughs and mouse-overs, to tracking cookies and web beacons. Advertising is the new porn industry, pushing the boundaries of innovation and achieving great things, despite a majority saying they would rather it wasn't there.

In all probability, we just need to face up to the fact that we are making a trade. If you want to know everything about me so that you can sell me stuff, then you can pay for the privilege. Why not come to my house, see the books on my walls, the food in my fridge and watch my children dancing around in the garden - that way you can work out exactly what it is I want and offer me a highly customised set of products, goods and services. I'll make you pay - hmm. Five hundred quid for full access? A thousand?

Or, maybe, that's not what we want at all. More realistically, if someone came and offered such a service, we would tell them where to stick it. To the point: nobody in their right minds would even consider doing it in the first place. But what if, instead, every time anyone came to our house to offer anything at all - a new kitchen or a charity bag - they happened to be carrying a camera, and if I didn't remember to tell them otherwise, they would be at liberty to flog the photos?

When it comes to the Internet, we are in danger of doing precisely that - evolving into a situation that nobody wanted because the vested interests were moving faster than the regulation, without anyone giving serious consideration to the consequences. I'm all for advertising - bring it on, I say - but let's not sleep walk towards a scenario where we find we have already given away our privacy, for free. Once it's gone, it's going to be a devil's job to get it back.