The explanation seems to be that after the 45 the low road soldier was executed in England , while the high road soldier was allowed home. At the time the coffin of the low road soldier, if sent to Scotland, would have been sent back by sea, the low route. This was the normal means of sending cargo to Scotland at that time. His spirit would have reached Scotland immediately after his execution, but he would never see his true love again. The released high road soldier would have had to struggle across land, and so would have taken the high route. Malcolm Rees, University of Buckingham