Guard, Conductor (senior, junior, assistant, temporary etc etc), Train Manager, Ticket Examiner (assistant or otherwise)
Right, deep breath...here goes with an attempt at an explanation.
Back in the old days, trains had a guard, or sometimes two with a junior "front" guard and a more senior "rear" guard. Guards were responsible for operational matters, timekeeping, safety, train protection in the event of an emergency etc etc. Tickets were inspected/sold etc by ticket examiners or inspectors, with an inspector simply being a more senior staff member with more authority.
Move on several years and
BR▸ started combining the two roles and giving guards commercial responsibilities (examining and selling tickets) - at the point the old-fashioned term "conductor" (which had been used in the US for years) was brought back into use: initially as "conductor guard" but then with the guard bit dropped.
Later on BR re-named conductors operating Intercity trains as "senior conductors" because of the implied prestige of these trains compared to local ones. That why on
FGW▸ WEst local services the staff are still called conductors.
Post-privatization some intercity operators stuck with senior conductor (including FGW for several years), with others adopting "train manager", with Virgin being the first I think. Others (
GNER▸ ) came up with the ridiculous "customer operations leader" and since some have reverted simply to "guard".
The rule book only deals with operational matters, not commercial ones, so all such staff (guards, conductors, senior conductors, train managers...) are referred to universally as guards in this context.
And lo! they were sore afraid. Here endeth the lesson.
