The reason this occurred to me was that I've recently ordered a set of destination blind transfers for a Limby Metro Cammell I've been tarting up (attempts to make my own blinds having failed miserably), and whilst I could easily think of a real station name as a suitable destination for the outer end, the terminus on my layout is fictitious so this obviously wasn't covered by the transfer sheet.
Then the penny dropped, all the dmus I've worked on whilst a Guard had (should have had... ) the same destination on either end!
In case this was a recent instruction, custom or practice however, I looked through the British Railway Pictorial volumes 'First Generation DMUs' and 'First Generation DMUs in East Anglia' to check, with the results described above.
When you think about it, a passenger boarding the train at most termini (and often trains in bay platforms) would only see the rear blind, never the front one. Not so long ago, having carefully put the destination up on the rear blind of my train, I was approached by a punter passenger customer who looked up at the blind and asked 'Is this train for York?' I bit my tongue and replied diplomatically in the affirmative, to which he replied 'Oh, I thought the display on this end showed where it had come from'.
OK it may well not have applied in all cases, but at least it got me off the hook for my model!
Prototype for everything though Ian - when the GN suburban workings used the headcode to identify the route rather than individual train, it would have been in order for a 'Cambridge Buffet Express' loco to correctly carry 1B66 on both cabs!