try this site for Wansdyke info.
http://www.wansdyke21.org.uk/wansdyke/wanwesteast/wanwest1.htm
which has some info on the Tump.
I'm working a CD rom with Robert for release sometime this year.

I'll be flying over Maes Knoll whenever the weather is fine enough.
I think we have to fly quite high to be above the aircraft that are landing at bristol ( 2,500ft ish.)
PeteG