I suppose the likelihood is that, after the merger, the Heralds largely remained on the old BIA routes, albeit in decreasing numbers. I seem to recall the UK was in recession in early 1980 so it may have been an opportune time to shed some routes and some aircraft. The F28s hardly started and the 1-11s were on charter business elsewhere on the network. Was there a long term plan to phase out the Heralds from the beginning, I wonder ? They were in the same class as the F27 and shared the same engines and big oval windows but not, overall, as successful as the F27.
I quite liked seeing the Air UK Herald based at LBA during 1984/85 although I'm curious as to why it appeared in the first place and why it only operated the Belfast route. More often than not it seemed to get a visual approach when coming back from Belfast. That's what I remember anyway.