Eight foot sheer plywood wall. 2 x 1" batten nailed along the top of it. Damp.
Jump, catch the batten, pull up, heel hook, lever up to get upper body weight in front of the hands, rotate hands, you're there.
It was the final obstacle on Saturday's Nottingham Rat Race. Great fun. I saw very few people climb it unassisted...
UK 4c ? 5a ?
Y