Wookey,
London-Rome would also be SE-NW.
I hope somebody will confirm this, but I would expect they would be route maps, oriented along the track from A to B, rather than oriented N-S or E-W, and that when operating a given route you would have loaded the relevant map.
Not sure how you coped with a significant diversionn though.
This was long before you could put the entire map of Europe and the display electronics into a little box the size of a cigarette package .....
CJ