OK, I have located the relay box (I think!) and photos are attached. I have removed each of the relays in turn and found that when the one on the left of the photo was removed the car would not start, so I assume that one to be the general ignition relay. The one on the right was removed (as seen in the photo) and the car started up quite normally (the engine had already been warmed up shortly before). I left off the relay and made the following observations.
On revving the engine the variator noise disappeared and did not return no matter what. The engine always returned to idle quickly and revved up quickly. There was no sign of the usual variation in idle speed when the revs where held at approx 1500/1600 revs (previously rose temporarily up to 1800/1900 and returned repeatedly).
I took the car for a drive around town where it previously had "kangaroo petrol" in slow moving traffic (ie when the revs were frequently around 1500/1600). This time it behaved flawlessly without any hesitation.
On acceleration (in second gear mainly) it picked up speed rapidly right through the rev bracket and returned normally when decelerating.
When I returned the relay to it's block the old symptoms returned.
Instead of opening the relay cover and testing the actuator, as recommended, I changed over the relay from the general ignition with the variator relay and it made no difference to symptoms (ie they were still there).
Do I still need to remove the cover from the relay and test the actuator?
What do I make of all this?