All depends which station in Kensington - go from Harlow Town to Liverpool Street on the train, then take the Circle Line (in either direction although eastbound's probably a bit quicker) to South...
Actually, the engineer controls the train's movement in & out of the station. The engineer is in control of the train movements with one exception- when a train is put together. A hostler...
Well, On the Aylesbury to Maryleone line, only Chiltern Railways are used but the mainline on the west cost uses Virgin. Banbury is the only station where these two collide