I grew up with London buses, on which that sort of arrangement was a complete non-starter (A) because the TGWU would never allow such a thing and (B) because, even if they did a complete volte-face, management would have regarded it as unsatisfactory in many aspects. I do, however, recollect my first encounter with the nationalised Western National in Minehead when working there during the summers of 1966/7 and the arrangements for their two 'trunk' services, the 215 to Bridgwater and the 218 to Taunton. Minehead depot was then still open and provided two of the three buses used on these jointly-compiled services, each running every two hours during the day, with a clockface hourly service from Minehead to the point where the routes split (forgive me, I can't remember exactly where after fifty years!) This splitting point was very significant, because buses from Taunton were timed to connect into buses to Bridgwater, and vice versa, and IIRC you sometimes had to physically change bus too if you were coming from Minehead in order to get to the destination on your original bus. Thus I believe only the two Minehead allocated buses ever worked into Minehead Bus Station/Depot during this period, one being a short Lodekka (LS) and the other a long Lodekka, with front entrance, a FLF. British Railways still maintained a Taunton to Minehead branch service then, which was used by the sensible plus myself! Anyway, it was an ingenious (I thought) way to avoid using an extra bus and you could never tell whether you were going to get the FS or Flf, both VERY foreign buses to a Londoner!