In October 1992 BBC Television aired a program called Ghostwatch, which it claimed to be a live investigation into supernatural activity at a private home in London. What started out as a normal episode turned frightful when a malevolent spirit attacked the investigators and manifested in the BBC television studio. A terrified reporter went on air and warned that by airing the investigation on live television they have created a “massive seance,” which unleashed the spirit onto the whole of the UK. There was a tremendous reaction by the viewing audience. Many viewers phoned the police in panic. But alas there was no ghost on the loose. In fact the program wasn’t even live. It had been recorded months before it aired.
Here is the show that aired on Halloween night 1992
Read more here: http://hoaxes.org/archive/permalink/ghostwatch