Thanks to the information provided I can run the layout in the early eighties and legitimately run the locos and trains that I particularly want to. That only leaves the track rationalisation at the North end of the station to justify. I assume that was done at the time the semaphores were removed? But rule one also applies and I can revert to the seventies occasionally to run 27s and different train formations.
The next step is to research said train formations. I have a couple of lists of passenger formations that have appeared on here and in magazine articles. I will have to spend some time looking at photographs to build up freight workings. As it will involve a fair bit of compromise, particularly in train lengths, I think I will aim for 'the correct flavour' rather than exact replication. Isn't that what many of us have to do anyway?