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Best described as a high frequency surging or hunting. I'm working on the supposition that 9 out of every 10 carb problems is ignition related.
I'm a bit colour blind and have never really got into wiring properly and years later I struggle when trying to diagnose this sort of problem, hence I am confused a bit as to which range on the multi meter I need to use etc. and what exactly I should be expecting. Ok, I can do the live, bulb and earth stuff but I don't understand why or how different ht leads need a different scale on the meter to get a reading. It's been suggested that the live feed to the coil may have over 12 v but not enough current, due to resistance in the wire.

I must say, starting hot or cold, idle and general behaviour is excellent, power is good, throttle response great at any speed, no misfire I can detect, but the chap at the rolling road said that the spiky graph is an ignition problem. But then, he doesn't like Aldon and lots of people do. And also, there is the rev counter flickering, 2 or 3 times a minute consistently, but no discernable miss or drop in revs.

Maybe it comes down to plugs being harder to light under compression, or a lean mixture condition or generally crappy mixture before the camshaft starts to work.

If the RR tech said he sees spikes and you are seeing tach flicker it is most likely a low-tension ignition problem and therefore, not associated with the plugs or plug wires.

Refresh my memory, is your Aldon distributor one with points or does it have the Ignitor module? Did you say you had tried a different coil? If you have points, are both the points and condenser new?

Brand new ignitor. Interestingly the coil resistance seems to have gone up to 4.5 ohms. The one I took off is the same, and I checked it out at 3 ohms before fitting the ignitor.
Stuff ought to arrive in the post today I hope. In the meantime I have been looking at the carb damper and will investigate the spring later too

Remember when measuring coil resistance that you need to disconnect the low tension wires first.

Bosch Blue coils can/will typically measure a bit over 4 Ohms so resistance that high is not necessarily bad. However, if your coil resistance actually changed that is unusual. Combined with the tach flutter it may indicate that the coil is/has failing or failed. Are you using a special high-voltage coil or a more or less generic coil? Unless you are opening the plug gap up wider than stock there is not a lot to be gained by running a Sports Coil or similar.