From a thread in the BA FlyerTalk forum in 2016:
Aircraft names disappeared with the Landor livery.
A320s: British Islands, eg. Isle of Jura
737s: British rivers, eg River Tamar, Thames, Spey etc
747s: British cities, eg City of Norwich, Edinburgh etc
757s: British castles, eg Windsor and Dover Castle
767s: European cities, eg City of Luxembourg
777s: Commonwealth aviators, eg Sir Charles Edward Kingsford Smith
ATPs: Gaelic stuff
HS-748s: Scottish Glens, eg Glen Fiddich
BAC1-11s: British counties, eg County of Cheshire
L1011s: Princesses or Roses (not sure which), eg Margaret Rose, 1.8 Vanden Plas
Tridents: nameless, possibly because they never formally made it into the Landor scheme
Seemingly the aircrafts’ names are still on plaques on the flight decks