I believe that Air Anglia was sold to British and Commonwealth sometime around 1980 and together with Air Wales and Air Westward was merged in that year with BIA to form Air UK.
BIA operations base was Gatwick and its engineering base was at Blackpool.
I suppose there was a westerly bias to their network serving Exeter, Southampton, The Channel Islands and The Isle of Man to name a few of their many destinations.
Air Anglia's main base was at Norwich, their rapid expansion fuelled by the North Sea Oil boom which resulted in a second base being established at Aberdeen. Their schedules from Norwich to Aberdeen and Norwich to Amsterdam were really their flagship routes. Many destinations were served predominantly in central and eastern Britain and also Stavanger, Norway.