Hi Brian
Thanks for your comments; yours was the encycolpaedic knowledge to which I referred in my first post! My apparant faux pas on the first class interior is very frustrating. I remember the gaudy orange interior decor, but was guided by a picture which appears to show an FO with the grey check moquette, and dark curtains in the 2E section of Michael Harris' book on Mark 2 coaches. I also remember seeing that scheme, but whether it was in a Mk 2E, I just don't know. The internet is a wonderful resource, but there is a severe shortage of decent colour photographs of mundane things (like the inerior of poassenger coaches and DMUs) from the 1970s and early 80s.
I'm afraid I like coach lighting. My current fleet is lit and I just love night-time operating sessions (I can turn off the lights, and the train room disappears, transporting me back to the late 1970s). The Hornby lights have a huge great capacitor which prevents flicker and is forgiving during running. However, the bar is too short, so it only really lights the middle of the coach. I have added additional LEDs to give light throughout the passenger compartment, but lighting the vestibules is eluding me at the moment.
Thanks so much for sharing your knowledge and expertise. All very impressive.