In reply to Andy Nisbet: Yep, 30m on the stretch of 9.1 single (Joker)is just enough. Not long enough for stacked abseils as you cant keep hold of the ends without tensioning them.
At busy times parties can put a long sling around the huge boulder behind the Bolster stone and abseil in the same direction but 40m is needed (the south wall direction needs 50m+ and is rough on ropes; north wall I've never tried) Get someone on top to throw your sling down afterwards. Explain carefully what is happening to other parties if you want to avoid an arguement, check for climbers on the short end and be patient/refuel etc.
The method used for years was to down-climb the short-side with the last person protected by the flake half-way down.
I abbed from this flake in October as I only had 17m total. Reaching it I realised that the whole flake could be looped but reckoned the rope would lock. With one hand holding the rope over a shallow spike on top of the flake tying an Italian hitch one handed was challenging. The length was alright but not an exercise I'd recommend overall.
Retrospectively I worked out that the last person must have climbed down to the flake, looped their rope over the shallow spike and down-climbed with tension from a belayer below.