I've never read any of his novels but a mate of mine was a very good friend of Pratchett's - he's one of the executors of his will.
Bernard tells a story of when he was round at Pratchett's and Steven Spielberg phoned to discuss the film rights to one of his books. Pratchett was very protective over artistic control and wanted the final say on screenplay and casting, something that Spielberg was reluctant to give up. When Spielberg's PA came on the phone, Pratchett put it on speakerphone and the conversation went something like this:
Hello Mr Pratchett, I have Mr Spielberg on the line for you
"Terry, it's Steven here, how are you?"
'I'm fine thank you Mr Speilberg'
"Terry, call me Steven please"
'OK Mr Spielberg'
"Have you given any more thought to our offer Terry?"
'I have Mr Spielberg and I'm afraid the answer must be no'
"Sorry to hear that Terry, this could make you very rich"
'I'm already very rich Mr Spielberg'
"Terry, I'm talking about very, very rich. More money than you could possible spend"
'Mr Spielberg, I already have more money than I could possibly spend, why would I need any more?'
Over the years Pratchett had rebuffed the BBC on many occasions, simply because he wouldn't relinquish control. I've always found it strange that Sky, of all media channels, was the only one to give Pratchett what he required.
I'm expecting that Wincanton may be overrun with Discworld fans this weekend on pilgrimage, seeins as the town is twinned with Ankh Morpork