You threw this out as a challenge to us, Iains:

"How many reading this have watched no porn on their own computers?"

It's clear from several of the responses that you are not in touch with the Mudcat zeitgeist. It's also clear that you want us all to chime with your own personal predilections. How disappointing it must be for you to hear that a good few of us are absolutely not with you when it comes to your porn habit. Still, as has been well said, that's your business.