Being mildly obsessive about these things, I've been digging into the SR Engine workings for 1958 and 1962 (thanks to the SR Email Group) - the first out of personal interest, the second because it's the nearest I can get to 1963!Yes, one way or the other.
If they had taken the loco back to shed, they would have left Waterloo at 4.30 following the empty train and booked off about 5am.
If I'm right about the 9.30pm down, they'd have done a bit over 8 hours, but rostered overtime wasn't unusual.
Nice little earner one way and another, but I don't know enough about enginemen's workings - maybe someone else here does?
Engines first:
The engine for the Up Mails actually worked through from Bournemouth, came off its train at Southampton Central around 12.30am, ran light to Southampton Terminus loco yard, turned on the turntable there and took water, and rejoined its train at Terminus station.
Meanwhile a second engine had come down light from Eastleigh, worked the Up Mails from Central to Terminus (tender first), followed it out of the platform and immediately backed on to the Down Mails which had arrived from London, and worked it onwards.
Crew next:
your Nine Elms men were involved with both: by 1962 they actually came down "on the cushions" (as passengers) on the 9.30 from Waterloo. They worked the light engine from Eastleigh and the Up Mails round to Terminus, handed it over to another crew, walked up the platform and took over the engine they were to work to Waterloo.
Simple really! You couldn't make it up - but such complicated juggling of men and machines was typical (of the SR at least).
As far as the book is concerned:
1. I think it's more likely that the bullion van would have been shunted onto the train by the engine bringing it from the docks, because the main line crew would be "last minute" backing down.
2. The booked engine for the Up Mails by 1962 was a Merchant Navy class (rebuilt, so not a "spam can"). In 1958 it was a West Country, and if you want to stick with Wadebridge, it was nothing unusual for them to stand in.
3. The engine they worked from Eastleigh WAS a West Country.
Oh, and BTW the Up Mails stopped briefly at Vauxhall "to set down invoices for Nine Elms."

