'Fire cover' simply means that there are enough appliances/fire engines available to cope with a further event. If I recall correctly, in an emergency at Heathrow the local 'civil' fire brigade would also attend and if necessary take over from the airport guys who would be able to replenish their wagons (trucks) and be ready to assume their role.
Gonzo
My No2 off-spring, an ATCO at Swanwick ( not a real one of course
) was flying to Malaga recently and sat next to him was the skipper of BA38. He said he is a really nice bloke and they had a fascinating chat, especially as No2's girl friend had also been in a crash several years ago - what the pax around them thought who knows!
Under the 'what a small world' heading, the co-pilot of BA38 was head boy of Gillingham School when my lot were there!
HD
Bren, as usual, wise words! Hope you are well. Brian W