ShyTorque, thanks for the clarification.
It would be interesting to know precisely in which specific case the issue of seeing an initial climb of a heavy B747 would infact fall outside CAS in the UK, mm_flynn mentioned Manston but I don't believe they operate a cargo facility there. I've seen B747 doing training flights there, yes, but that's a whole different ball game.
Interesting to see the difference between the FAA and the CAA interpretation of the rule. The FAA includes the "safety" aspect in the speed limit (which is also valid inside of CAS) whereby the UK only have outside CAS, and I guess it's mostly for see-and-avoid timing for aircraft with high closure rates.
Ciao, Luca