It was Marcus Waring, but nothing about laying on a hill. We layed some hedge a while back but on the level. Yes, pleachers laid in opposite directions will look a bit funny until they grow, but so what? It's not a competition, it's your hedge and you can do what you want.
One thing we did discover is that if you plant whips in gaps they don't grow because they are overshadowed by the rest of the hedge, so best to fill in with pleachers. You could leave some to grow on if they're not tall enough to stretch across.