I'm trying to figure out what a rather odd short film is that I saw on BBC (I think) a few times when I was a kid (in the 70s/80s). It involved some animated arty types moving around a field, appearing and disappearing into the ground so a soundtrack of jazzy snare drum. I'm pretty sure it's being pastiched in the section of S1E3 where Brian and Vulvas act is remembered by Brian and then imagined by Tim.
As I have the original release of the S1 DVD (withouth the homage-o-meter) could someone have a look and see if it says what they are referencing there...
cheers very much!