"Its years since I read Len's book, which was compiled from his notes after he had passed away. Surely he wrote The man's L and the ladies R hip. And not the man's R and the ladies L hip."
As it would be essentially impossible for the man's L hip to contact the lady's R in either promenade or close position, we can obviously conclude that his warning was as stated, against the thing that a sloppy couple easily could allow to happen, which would be his Right hip contacting her left.
Promenade is a subject that confuses many, but it can actually be easily understood if you simply consider for a minute that having the foot positions "open" means that the feeling in the body will not be one of being opened out, but rather one of being stretched very "closed" to the partner. The body is stretched in opposition to the opened out foot positions.