Are we talking about the Astoria 1990 show?? I can't see that being called 'Big Drum' as it's just an atomspheric keyboardey type piece with no drums on it at all. (they did however have a drum based intro on later tours, but this was simply the intro from the 12" remix of 'In Charge Of My Heart', which they then went straight in to.)
I always thought that the 1990 piece it must be an original piece of theirs, but I am sure I heard it being played somewhere a while after and it was credited to Joan Armatrading.
This could be possible as she and Roger were acquainted (she speaks on 'Don't Lose Your Head' and he originally wrote 'Heaven For Everyone' for her to sing).
I'm not sure of anything else on this I'm afraid, and I could be wrong - anyone got any better facts?