Those of you who have been following our story of May 20th about the David Gilmour and Guy Pratt musical contribution to the Nick Laird-Clowes soundtrack of a documentary for Greenpeace, may well have now given the song itself a good listen.

The 20 minute film, directed by Nick Broomfield, tells the story of the activists who scaled the 220m chimney at Kingsnorth and the landmark case with supporting testimony by the world's leading climate scientist Dr James Hansen of NASA. It's a remarkable behind the scenes look at Greenpeace and the brave people who are willing to put their liberty on the line for what they think is right.

It includes a new song, 'Mayday' ("a meditation on street protest - circa '09") which includes David Gilmour on backing vocals and guitar, and the bass of Guy Pratt. Recorded over the May bank holiday weekend, the song is now available to download through this link, and you can watch the entire documentary via a stream (including an HD version) at Greenpeace.org.uk, where you can also order a copy for download (or on DVD).