Haven't seen the film but I know that some friends of mine were involved with the soundtrack - Robin Jeffrey, Robert White and Tim Laycock. Tim would have been playing concertina, I imagine, Robin usually plays fretted stringed instruments (and occasional percussion) but as Robert plays anything one can blow down, pump with ones elbows or beat a rhythm on, he could, feaibly, have been playing anything (or, pretty much everything!)! They are all members of New Scorpion Band, by the way, website at:   http://www.new-scorpion-band.com