I thought it was conceived much earlier than that. Or is my memory deceiving me?
You were probably thinking of CASTOR, the Corps Area Stand-Off Radar old sport.
The Corps being 1 (BR) Corps of the BAOR back in the 70's. I worked on the concept phase in 1978.
The AAC were impressed with the US Army OV-1D Mohawk and thought that something similar would be useful.
It's a long sad story but it eventually mutated into Sentinel, by which time there was no BAOR and no massed ranks of Soviet armour to spot.
Cue the 'ASTOR isn't CASTOR' brigade.
It was an aircraft looking for a job in a world which had changed.
Lots of very talented people used it to the best of their ability and no doubt it did some good.
Now that it has gone .. who will miss it?