The national trust are going all green - as a conservational body they approve of the idea of reducing their impact on the environment, so they are starting a number of 'green' initiatives. One of which is a green energy tarrif in association with npower. Another is using renewables where possible.
I spotted this anomoly at Hanbury Hall - I couldn't find out much about it, but it does look rather incongruous seeing the ultra modern thin film solar panels, mounted on a 300 year old wall in front of a 500 year old house:
I /think/ its for powering a fountain - if anyone figures it out for sure, let me know !