That might be it Kato. I'll keep digging.
And funny you should mention Crownhill Fort. My plan was to use either Tregantle Fort (which is still used by the MOD and in superb order) or Scraesdon Fort (which would need alot of work done to it) or either both as a kind of FOB into Cornwall. They could be used for guarding the sea and land on the Cornwall side of the Tamar against the Dukey forces and as FOBs for raids into Cornwall.
As air-power is not a huge problem in TW2000 the solid granite walls would make a nice bit of cover.
Here's a picture of what I mean.
http://www.cyber-heritage.co.uk/tregantle.jpg