Don't know who plays on that particular song but regarding the soundtrack for the film, one reviewer on Amazon notes that "half of the future Led Zeppelin play on this disk".
Makes you wonder.
Here's a link:
It appears the bassist was Bob Lang of the Mindbenders. The Mindbenders continued on after the departure of Wayne Fontana, starred in the film with Lulu, and played the title track. Here's the link: http://members.tripod.com/rant58/id369.htm
Not only is that one of the greatest movies ever (one can spot future Power Station vocalist Michael De Barres as one of the students), but that is a fabulous single. I don't hear Jamerson anywhere in that line- more of a Beach Boys thing with the muted playing- but it kills me every time I hear it. Good old Lulu.