I am slightly surprised by the lack of alcohol, I've been in the same situation give or take in CW and the crew were extremely good at keeping us refreshed for the 4 hours we sat on the ground (indeed, come arrival, I rather regretted the last few glasses). Particularly given you were in first, it should not have been beyond the capability of BA to locate further supplies of 'duty paid' bottles at their home base you would think so rather disappointing. I don't think you'll get anywhere with compensation on the other hand...