Suppose you have 15 minutes to while away waiting for the train. Why not pull out your mobile phone, punch in your pin number and download a Playboy movie for as little as £5? Not interested? Of course you’re not; you’re a Spectator reader, for heaven’s sake. But there are plenty of people out there who are, and they’re not only bringing in revenue for the niche market of mobile porn, they’re actually driving the development of mobile technology.Three years ago, when third-generation mobile phones were first launched in Britain, the joke was that 3G stood for ‘girls, gambling and games’. That has proved substantially correct, though it could equally well be ‘girls, girls, girls’. One specialist research firm, Juniper, estimates that the market for mobile adult entertainment services will be worth more than £700 million this year, reaching £1.