Ref the Fisher (LCY) servce, i've read that link and can't see any problem with the Unite side of it at all. Far from them rejecting an a la carte service it clearly says
Originally BA brands wanted ‘a la carte’ flexible dining for 32 people. Some initial trials were done and it was obvious that this was not achievable with 3 crew. BA believe that 3 crew can deliver a Club World service however. The aircraft delivery is the problem as we will not be able to do many trials. The aircraft will be similar to the A319 however.
Seems to be reasonable to shelve an original idea if trials show it's unworkable.