Yeah CC have told me that before on a lot of flights on WT+ return. I wonder if it's just only the 788/789 though. I've certainly had it on some return flights in WT+ but I haven't worked out if the aircraft is at fault or maybe some outstations have it chilled somewhere. It is a bit poor BA haven't found a way of chilling some bottles. Of all true modern technology on the aircraft and they haven't got a fridge.
Maybe I should bring a bottle from the lounge and serve the cabin - although I wouldn't want to be filmed and shamed on these forums for doing such an act!