The illegal broadcast was investigated by UK authorities who were unable to determine the source of the signal or who might have sent it. It is assumed that the broadcast was a hoax perpetrated by someone who sent a signal powerful enough to override the station's VHF transmitters, but in the past 30 years, no one has ever claimed responsibility for the hijack. (My own research into this incident revealed that an unnamed group of students were suspects at one point, but that no evidence beyond mere suspicion was ever offered to support that theory. Another suspect was a person with connections to the British broadcast industry who was known as the "Cosmic Cowboy," and who may have been assisted by a cabal of hippie friends. Again, there is no proof for that assertion, either).
It would later be confirmed that five major transmitters were hijacked simultaneously, a rather spectacular feat at the time that would have required considerable transmitting power and a coordinated terrestrial effort.
The event caused panic in some parts of the local population for people who believed that the transmission was actually coming from an alien civilization.
Because this incident occurred over 30 years ago, it has all but faded from the memory of most people and remains primarily of interest to ham radio enthusiasts and those who study UFO history.
The person (or entity) responsible for the transmission has never been heard from again.