hmmm...our train has been dispatched early from Christ's Hospital twice in as many weeks. 07:42 is 07:42, not 07:41. On both occassions someone has missed the train. Black Mark Southern!
Although station clocks are supposed to be synchronised they're often out. I know of one that's been wrong for weeks Why do people leave it to the last possible second to arrive for a train anyway?
Dispatch time should be by the platform clock where it is correct with the dispatch procedure commencing thirty secobds prior to published departure time. I may take a discrete look into this if I get a moment.