Re: 7 trolley dollies, one packet of crisps!
Beagle did you not read the posts where the reasoning for crew levels were explained?
a) Crew levels are determined by the number of Club passengers booked on a flight.
b) The legal minimum on the A321 is 5 cabin crew, the BA maximum is 7. You will only ever find 7 cabin crew on a flight with a high Club load.
c) The crew matrix was formulated 'pre crisp service' so will probably be in the course of being re-evaluated as I type!