I spent time on 85 Sqn 1972 - 1975. We towed banners for air to air only. The banner was a mere 900ft or so from the tug and the Canberra was known to appear in the gun camera of the Phantom and Lightning.
On 7Sqn at St Mawgan from 1977 to 1980. We towed Rushton targets some 18 to 24 thousand? feet behind the aircraft.
I don't remember a Blowpipe ever coming close to the target. Rapier was better. I once flew two sorties on a Baltic range for a German Geppard. The Rushtons were destroyed within a second or so of being acquired.
The big bombing raid that completed the Air Day was always great fun.