Good point Ella.
I seem to remember though that there was an operation a couple of years back that was operating to Toronto from Birmingham.
They were doing a routed from B'Ham with full fuel load to Toronto, Then full fuel load back to Exeter. THey landed at exeter and chucked the Exeter PAX off and loaded the Toronto bound PAX but no fuel. Flew up top B'Ham and changed the B'Ham PAX over as well as recatering and cleaning as well as doing the full fuel upload.
I know they used either a 757 or 767.
I am fairly sure they carried no cargo though! I never saw any go on at Birmingham or Exeter.
FlyBlu will have a problem to match the BA ticket price to Orlando. It's only about £360.