I need to EXTEND the suspension, not compress.
Anyway I used a piece of timber to extent it while fiddling around trying to pull the bag out.
Now I am pretty pissed off as one of the Arnott bags was missing the C clip that goes onto the hose at the top of the bag where air goes in. I thought "no worries, I'll just use the factory clip" but it does NOT secure the Arnott bag!
FFS now I've got my car in pieces and can't drive it because 1) Arnott made the fitting slightly different and 2) the Air line retention clip was missing from my right side bag!