Reenan and an examination of his unsophisticated receiving system (which consisted essentially of an Icom wideband scanning receiver and a conventional television antenna), showed that the recording was most likely to have been made as a result of a local tapping of the telephone line somewhere between the female party's telephone itself, and the local exchange. Furthermore, narrow-band spectrum analysis showed this 50 Hz "hum" to consist of two separate but superimposed components, possibly indicating a remixing of the tape after the initial recording. The spectral frequency content of the tape was demonstrably inconsistent with its supposed origin as an off-air recording of an analogue cellular telephone channel but quite feasible if the recording had been made via a local-end direct tap. As well as the strong technical case he made against the recording, Nelson established two other salient points. The first was that Gilbey's mobile telephone was registered to the Cellnet network. Secondly, the Cellnet base-station transmitter site in Abingdon Town, the data channel of which was the only one receivable on Reenan's receiving system at the time of his visit, was not in service at the date of the alleged telephone conversation; it was first commissioned on 3 March 1990. It was therefore not possible that the purported recording could have been made off-air by Reenan or Norgrove in December 1989 or January 1990. With regard to the data-bursts that had aroused the suspicion of Audiotel International, Colloms and Nelson stated: "We are forced to conclude that these data-bursts are not genuine, but were added later to the tape. They originated with a locally-made recording, and show that an attempt has been made to disguise a local tap by making it appear that it was recorded over cellular radio." Telecommunications company Cellnet admitted that it had automatically conducted its own internal investigation after publication of the "Squidgygate" transcript, because Gilbey had been speaking on a Cellnet phone. "It is a very sensitive issue if a cellular network has been bugged," said Cellnet spokesman William Ostrom: "We wished to satisfy ourselves exactly what happened." Cellnet's inquiry, claimed Ostrom, had "replicated" the findings of Colloms and Nelson: Cellnet announced that it was "completely satisfied that we can dismiss this as an example of our network being eavesdropped." Government reaction Suspicion about responsibility for the "Squidgygate" leak focused on the United Kingdom's security service, MI5. Home Secretary Kenneth Clarke said: "The