The only rule for CC that the CAA regulate is the implementation of the (daft) EU rule about block flying time for CC which was introduced sometime in 04/05.
Thats untrue. The CAA are the regulatory authority (partly subservient to EASA) in the UK, and its their regs that apply.
Try CAP371 - Avoidance of fatigue in aircrews, from which the BA scheme is derived.
CAP 371
Some of Betty girls assertions arent quite correct (time after arrival doesnt count for example) but the essential thrust is. Far East - London cannot be done legally without the cabin crew all getting 3 hrs in the bunks. Under CAA rules however this need not be consecutive, so if BA wanted to have a middle meal service, under CAA regs it could be done by splitting the breaks.