PC767,
What Skipness 1E was saying, in response to Hunterboy's post, was that there are several routes where the originating traffic is only at one end, and the return sectors are generally those punters returning to base. So it is possible to operate routes quite happily with the bulk of your traffic originating at one end. Yes, they have to go home at some stage.
In other words, you don't see nearly as many Floridians or Spanish coming to the UK, as you see UK'ers going the other way, then home again.