There was an excellent program on BBC 2 Scotland last night - Britain's Ancient Capital - Secrets of Orkney. The entire program is well worth a watch, but from a climbing perspective there is an intresting section where they climb North Gaulton Castle with Cubby and Paul Tattersall (although I'm not sure who was doing the climbing).
Link:
http://www.bbc.co.uk/iplayer/episode/b087vh70/britains-ancient-capital-secr...
Climbing starts around 32:00. Enjoy.