This is on tonight, BBC 2 at 9.

http://www.bbc.co.uk/programmes/b0120dxp

I imagine this is going to be pretty heavy going, but I'm interested to see what he has to say and see just how much the disease has affected him since the last programme he did a few years back.

Depressing I know - favourite Pratchett books? Mine is The Fifth Elephant, followed closely by Men At Arms.