The wall has a number of inscribed blocks. The extreme right hand one, slightly set apart and where the path starts to steepen is the one- Inscription reads "Laid my Mound Voluntary Workers Siliver Jubilee Day 1935". Stand on the upper edge, and climb direct.
I'm not too certain of the grade. It was one of the more technical things I've done, and it took a good number of evenings to work (I'm not really a boulderer), so the grade is pretty much a guess.