Just been looking on wikipedia and found this interesting link to the transmitters at rugby.
Subterranea Britannica: Sites: Rugby Radio Station
I wonder if thats true.
This site is earmarked for a new town I believe. They're slowly taking the masts down now as they're defunct apart from the rugby clock and thei 'secret' use.
Although protesters to the new town did manage to delay several being blown up.
BBC NEWS | England | Coventry/Warwickshire | Rabbits delay masts' demolition