Although the I can't comment on LHR specifics, I can say 100% that toaster use in public areas is prohibited in certain out stations, as set out in each of the separate internal bylaws. BA won't have a great deal of say in the matter.

You can just see it now; 200 passengers benefit from an impromptu shower in T5 GC due to sprinkler system fiasco!

Many a year ago, MAN used to serve toast and advertise it as cold toast. It was pre cooked in the kitchen before the lounge even opened.