Until recently (say) 4 or 5 years ago, perms could only be ridden once a year - in either direction. So you got the chance to ride the event twice annually.
Since then the once-a-year rule has been dropped, but I think the direction issue was allowed to stand (good idea)
.
I know for a fact that 3peaker allowed his perms (bar one) to be ridden in either direction, his routes were supplied in bi-directional format - including maps. Stephen might be able to shed some light on the issue.
Mike Wigley, (I believe) was the main driving force for allowing perms to be ridden as-often-as-you-like. (Good idea)
, perhaps Mike could also enlighten us all.