Grid ref accurate, but it's nearer to Todmorden than Hebden Bridge. Make for Great Rock on Eastwood Road, walk down Eastwood Lane, past the house where lane swings right, and find style in wall on right (just after next lane on left). Walk on the path through styles in walls to wooden style where boulder is.
We went to have a look on the way home from Solstice at Castle Rigg- no tape measure- measurements approx; length 62cm, width 39cm, depth 30cm. The 4 larger cup marks are approx 23cm and 14cm apart. 5th smaller cup shown on artistic image not so defined (due to being walked on?).