I think that I have now found the answer
here in post#3 by PN.
A summary of the answer:
Glasgow Bombplot had closed before the end of the '60s. It may have been the one that moved to Gernish in the Outer Herbrides.
The other high level bombplots at Ouston, Haydock and Kenley all closed and moved to Tumby near Coningsby, Lindholme and Dunkeswell.
Ouston had been able to score popup attacks on Newcastle but the presence of the increasingly busy airport and the undulating terrain made it unsuitable as a low level plot.
From time to time one of the plots relocated to Sleep, usually for competitions.
So the remaining question is:
Can anyone provide the dates when Glasgow Bombplot was active?
YS