Didn't this cover your BAA/CX point? IIRC the new gauges don't have scales and I'd be very surprised if they are bag counting per passenger. I thought the rules were specifically aimed at size. BA has decided on one set of rules about number(s) of bags at the max regulation size, other airlines may differ
BA has adopted the
maximum size and number of bags the BAA/Dft will allow. Even if another airline says you can take 100 bags on board with you, the BAA will turn you back!
The airlines themselves have brought this about by failing to regulate their own policies effectively.