When you walk into Interclimax in Amsterdam, it's like walking into a sexual Big Brother. With more than 1m visits a day, the Interclimax site is an extraordinary commercial success, and adult channels in the UK are beginning to look at these businesses to see what lessons can be learned. While broadcasters in the UK scratch their heads and wonder where they fit in with this technological progress, young, dynamic companies such as Amsterdam's Interclimax, which we found and filmed behind the scenes for Channel 4, have solved the problems and are making big money. It has been so successful that in as little as two years, pornography will have broken through the barriers of broadband technology, building on its current pre-eminence in ADSL and video on demand. When Channel 4 asked us to make a series about the liberal city, we saw first hand exactly how the sex industry is driving internet business expansion.

The epicentre of the development of adult material via the web is Amsterdam.