Hannington transmitting station is a television and radio transmitting station located on Cottington Hill near the village of Hannington. The transmitter is actually in the parish of Kingsclere. The station provides broadcast services to Berkshire and north Hampshire, and includes a 131.4 metres (431 ft) guyed steel lattice mast. Surmounting the mast is a GRP aerial cylinder, which contains the UHF television transmitting antennas, which brings the overall height of the mast to 151.9 metres (498 ft).
Ofcom confirms that Hannington's digital broadcasts are severely attenuated to the East so as not to cause co-channel interference with Guildford transmitter, see picture.
On Saturday 26 November 1977 at around 5.10 pm, broadcasts from this transmitter were hi-jacked by unknown agents who blocked the UHF audio signal of transmissions from the then local ITV station Southern Television and broadcast their own audio message purporting to be from Vrillon, an alien from an institution calling itself the Ashtar Galactic Command. The message, transmitted over an ITN News bulletin and a subsequent Merrie Melodiescartoon, lasted six minutes.
Despite extensive investigations by Hampshire Police, the Independent Broadcasting Authority and Southern Television, those responsible have never been identified, and the potential culprits have ranged from students to university professors to disgruntled television technicians.