Recently did the L to R version, which took several attempts bash into submission and recon its bottom end 7b+.
Dave graded it a few years back at V9, and it was mentioned on javu in the 'hard granite' list as a top traverse (really hard to navigate but its still there somewhere); which recently moved to V8, then to V7
Don't think its 7c and its defo harder than 7a and its a good power endurance, heal swapping thing of beauty, half a grade easier if you go R to L, and allegedly 8a if you do a there and back.
Its easily harder than the Cream Traverse at Hound Tor, which is something else I would recommend doing if you haven't already, along with Arkham at Bonehill, the three problems make up my most favorite
Dartmoor Granite is notorious for being a buggar, and best left till temps < 8 deg C but when they go, they're brilliant
Just a shame its so limited, but the rumor mill is in full action about a new area, that will soon be published, with a pile of golden problems...