The linked thread is excellent and brings back a lot of memories for me of travelling from the midlands to east anglia in the late 1970s and early 1980s. Sometimes from Birmingham, sometimes from Nuneaton, occasionally from Hinckley. Oddly enough I was discussing these trips with my dad only last weekend.
As others said, progress was often sedate at best, and timekeeping wasn’t great either, partly because of the number of flat junctions with main lines, partly because back then connections were often held, especially on secondary services, and partly because the 31s weren’t the greatest, although that improved with the 31/4s.
One thing my dad mentioned, which I didn’t see in the original thread, was that he understood that up until privatisation there was some sort of agreement whereby “midland men” didn’t go east of the ECML. No idea if it’s true but the Saltley driver mentions route learning to March in the 90s so it could be
The best thing of all in the 70s was doing the trip in the winter with a goyle that was properly steaming and getting a mk1 compartment in the first carriage and cranking the heat up. Beautiful