As mentioned in today's Guardian. They want you to register, but once you do you just get a link, so, er, here's the link!
You will need to register at Audible, though, if you're not already a member, and that includes giving them credit card details, annoyingly. Guardian's T&C says you don't need credit card details, but I couldn't see how to register and download without them.
It's also got an annoying download manager you have to install rather than just giving you the MP3. The file itself appears to be DRMed, although it does let you copy it to various devices. Still, it's free, eh? Not encouraging me to use Audible for anything else though.
Very funny clever comedian and satirist, but I've not heard this show yet. Looking forward to it, though.