Just what I was looking for, thanks. Was the Fort William Sleeper plus MotoRail one of the London departures? Also were these from Kings Cross at the time? What would the traction have been before the 37s took over for the WHL?
The Fort William did originally go from King's Cross, I think, but all Sleepers had diverted to Euston by about 1988, as the East Coast Main Line was frequently closed overnight during electrification work. I think the idea was to return some sleepers to the ECML after electrification - hence the blunt-end cabs on the 91s - but it never happened. The sleeper market was starting to decline somewhat by then, and BR had far more Mark 3 sleepers than it eventually needed. It was easier to concentrate all the Anglo-Scottish sleeper traffic on one line.
Traction on the Fort William Sleepers over the WHL was Class 26s before the 37s. The changeover there was some time in the early 80s. On occasion in the early diesel days, the exceptionally dreadful Class 21 and 29 locos made appearances, usually in pairs because they were so unreliable!
Information on Sleepers is quite hard to come by - they don't tend to get noticed or photographed by many people! A lot of the little variations and changes over the years have probably gone completely unobserved. There's certainly not much in the way of books about the history of sleepers, and I think this is a major gap in the market.
My own particular interest comes from two and a half years of working for Caledonian Sleeper.