Apparently, eight million of us in the UK would like to hang a piece of original art on our walls. Not only that: we would like to own it. According to the Contemporary Art Society, which buys artworks for municipal galleries across the land, we are all closet Saatchis, only lacking the finances and possibly the confidence to follow Britain's best-known art collector. Indeed, he is the only one most people know. Whereas American collectors are happy to have entire wings of galleries - or, indeed, entire galleries - named after them, and are wont to appear on the internet smiling broadly in front of their Damien Hirst spot paintings, British collectors are almost fanatically secretive.

That is perhaps why so many people turned out on a recent snowy night in London to debate the value, and point, of collecting. Well, there were two reasons. First, the event offered the intriguing presence of a pair of real-life collectors. Second, it was held at Sketch, the wildly chic venue in Mayfair that serves tea in oval china bowls and patisserie with edible flowers.

The event was organised by Blood, a group that arranges gallery trips and chats with art insiders for would-be art collectors. On this occasion, the professionals were Isabelle and Jean-Conrad LemaItre, a French, London-based couple who have been buying since 1982. This was when Jean-Conrad, having been to a public exhibition of abstract art in Barcelona, was amazed to see a painting by one of the artists in the show for sale at a private gallery. He immediately bought it, kicking off a passion for those little red dots that indicate a piece has been sold.

For the past ten years, he and Isabelle have been focusing on video art, which they insist is a perfect genre for the contemporary collector. Isabelle explains that they like to invite people round to see their latest video - "just as, in the olden days, you might have said, 'Come and see my etchings'." Presumably the other meaning of "Come and see my etchings" has yet to make the leap into French parlance.

The LemaItres appear to have made pretty decent inroads into the field, owning pieces by the Turner Prize-winner Gillian Wearing, Mark Wallinger and Tacita Dean. They dismiss notions that a spool of videotape is less "precious" than a canvas, and explain that they buy only original pieces or work in limited editions. It's not a simple purchase, either. Artists can dictate who buys their work and, once it has been bought, how it is shown. "Some prefer to have their work screened on a projector, some to have it screened on a monitor," explains Jean-Conrad. "Why is this a problem? This work is like a child to them. You wouldn't just let your child go to anyone, would you?" He brushed aside questions about discounts and investments and the considerable status of the collector from both the private sector and public galleries, which perhaps hope to be lent an important work. These, he said, were not good reasons to be in the game of collecting.

Yet they are reasons, and perhaps why Blood members are so keen to join the group's monthly trawls around the city's galleries looking for the next big thing. As our market expert explained, if only you'd had the foresight to buy Hirst's shark, you would now be sitting on a tidy profit. Having bought it in 1991 for £50,000, Charles Saatchi sold it in January for nearly £7m.