Vapourer... yes, Cossor 901; that's it. I'm sure it was at Farnborough for a while, atop a concrete tower somewhere in the NW part of the airfield as it could be seen from the road from Fleet past the old gas turbine place. It sure was poky as they could see traffic landing at the Paris Airports! If my brain is playing up, I apologise.
Only time I visited Boscombe was in 1971 when the Dove I was aboard as a "safety" pilot during SRA training had to div to Boscombe due to fog at Hurn. Maybe that's when I saw the Cossor????