Might be of interest:
I live a few miles from Lindisfarne (Holy Island, home of St Cuthbert).
The priory (now ruins) plan is here:
http://www.english-heritage.org.uk/c...ry-phased-plan
It is a nice location for a defensive outpost, only reachable at low tide.
There is also a castle here.
It was targeted by the vikings in its day.