In reply to Will Cat:
I've done this twice in the late 80's.
I'd say technically about 5a but nerves make it feel like 5c.
The first crux is the walk through the railway tunnel.
At lowish tide you can then get to the base of the Parson by a leap over a watery channel.
Top pitch is quite scary as you have to pull on conglomerate.
Final crux is escaping the owner's attention in the garden at the top.