Hi Bill. Thank you for your kind words. It's nice to see you on the forum here also.
It does indeed sound like the two jobs (road and rail Shunter) are of similar ilk. Sadly, however, the Shunter on the railway is one of the lower paid grades even though, as you say, they can bring a yard to a standstill if they don't know what they're doing. There are usually a number of Shunters in a railyard or carriage sidings under the control of a Foreman. The Foreman has a list of trains that need to be formed and the times that they will be dispatched. It is the Shunters who then have to go out into the yard and do the dirty work of putting them all together in the right order. It's a dying art though as nowadays most freight in the UK is shipped in "Block Trains," as they are termed, where there is a contracted service with a set number of wagons and they arrive and depart from a yard or private sidings at the same time each day/week irrespective of whether they are full or empty.
Malc, "flagman" is the term used on the shop floor amongst the working staff. Handsignalman is the official term quoted in the rule book (and used more so nowadays where railway employees no longer come from a line of railway families.) In the daytime hours these Handsignalmen use flags and dets (though emergency speed restrictions nowadays are usually covered by Daleks.) At night, obviously, they use lamps.
Cheers
Dave