Although all 777s operating out of LHR should be New Club World, and should have been for some time, this isn't always the case.
This summer, for example, on at least one occasion (and perhaps more frequently than this) BA was using a three-class 777 with the "old" CW on the Hong Kong route. (These have a better choice of "good" CW seats than the four-class 777, in my view.)