My vote goes to Dar es Salaam:

I fly in NCW (and F until they stopped it) on the DAR-LHR route at least six times a year and really take exception to the consistently disgusting food they serve on this route. Overcooked garbage made from sub-standard ingredients is the order of the day ex-DAR.

I believe it to be the worst catering on the BA network and have complained numerous times verbally, in questionnaires and via email to absolutely no avail. BA obviously uses a local company (but part of one of the big aviation catering companies, I think) to provide the food for these flights and it's really not up to standard. Crew members I've spoken to are of the same opinion and always say they'll mention it in their report. I'm not sure that the powers that be are listening though... I've now resorted to a big pre-flight breakfast when flying BA out of DAR. Then selective 'club kitchen' nibbles. Sad really.

If you have taste buds, is this the worst place to fly BA longhaul from?