Right, I'm pretty sure I've discovered why the electronic ignition failed. Please have a look at the thread entitled 'Electronic Ignition' and my post on May 6 2017. See the image of the inside of the distributor? See the black plastic 'collar' around the distributor shaft?
Looking around the engine compartment this morning, I found resting against the bottom of the inside wing HALF OF THIS COLLAR. Now my guess is than when the French mechanic took the distributor cap off, or the distributor out, half of the collar fell out. With this in a damaged state, the sensor would never have been able to send it's magnetic pulses to the coil and then to the spark plugs.
I thought when I fitted it that it was a damned fragile thing is it has four vertical cuts in it, like an annular chocolate bar. Perhaps the other half of the collar is inside the distributor?
Well Paul, it looks like you've solved the puzzle. Very bad luck I reckon, but I do agree that the sleeve is delicate and I noticed, a tight fit. I'm hoping that Aldon will be helpful and understanding when you explain what has happened.