As with much of peak boulders, difficult to know if done before or not, anyway here goes....
There is a fantastic low and flat boulder directly up from the last slab area of Clifftop area.
Starting sitting at seam and pocket, hook and slap your way along and around the blunt arete [crux] and mantle out above the flake line, great. Loz 6B.
Sitting start [easier with mat, so no mat], pull into the flake using nipple out right, and mantle out, again good. Tog 6A+