A recent dip into my inbox made me think there was a mega pre-Christmas sale on at Quark. Alas not.

Formerly the market leader in DTP (desktop publishing) software, the past few years have seen Quark's Xpress haemorrhage market share as publishers and designers turn instead to Adobe's more cost-effective and PDF-friendly CS (Creative Suite) and CS2.

But Quark has great faith in its latest release, the much-trumpeted Quark Xpress 7.0. Colleagues at Digit magazine weren't hugely impressed, truth to tell, but when I received a mass-mailer email telling me I could buy Quark 7.0 for a mere £250 ex VAT, my interest was piqued. (Well, I was mildly diverted. I've got CS and I still think my next DTP purchase will be CS3, but a brand new professional-standard package for a little under three hundred nicker is not to be sniffed at.)

Quark advert

Spot the delibarate msitake

Alas, it was an error. This was the upgrade price, and the purchase price had been missed off. Today (two-and-a-half weeks later) I got the correction email, telling me that the correct price is, in fact, a healthy £880 inc VAT. Diversion over.

As well as being hugely embarrassing, this kind of mistake is something of a legal minefield – particularly in the internet age. An advertised price is regarded as an 'invitation to treat'. In other words, it is the green light for a customer to make an offer, but the retailer does not have to accept it. However, the Consumer Protection Act of 1987 makes it a criminal offence to give consumers a misleading price indication.

The Act covers giving misleading price indications 'by any means whatever' (so a marketing email would certainly count), and retailers in England and Wales can be fined up to £5,000 in the magistrates' courts each time a consumer is misled.

It's a defence for the retailer to show he or she acted diligently and took all reasonable steps to avoid giving the consumer a misleading indication. But it's no defence to simply claim it was a mistake. Quark would need to show it had sensible systems in place to stop this sort of thing occurring.

In response to complaints, local trading standards officers could take action in the part of the country where Quark trades or where consumers happen to live.

So why would Quark draw attention to this potentially damaging mistake in a further email? Well, apart from being fine upstanding folk, as I'm sure all Quark staff are, there's the small potential for the company to end up having to honour hugely under-priced deals.

If a retailer accepts an offer, even at an incorrect price, they are legally bound to honour it. In the corner shop this isn't much of a problem – verbal contracts aren't worth the paper they're not written on. But on an automated website this can lead to all sorts of legal fun and games.

A few years ago high-street stalwart and purveyor of laminated catalogues Argos almost had to give away a few £300 tellys for £3 because of just such a situation. A decimal point slipped on the website, and contracts were entered into.

Quark will be fine, of course, because its error was made in good faith, in an advertisement rather than its online store, and because no-one would gain from taking action. But I suspect there's a brand new passion for proof-reading at Quark towers...