Thank you, curro101.
With regard to my last post - I panicked when she cut out the third time, and was trying to start her whilst she was still in gear - hence third time lucky when she started.
No oil leaks onto the circuit board which was also checked and found to be fine, so have not had the K40 connections resoldered. I am sure she will be fine now, and thank you for your post, Best regards, Ladynoyes
Can you edit the OP to remove this info about the third start? It might mislead the investigation.
And visual inspection of the K40 is good when the solder joints have overheated, but it would be useful to clean the contacts of the relays in the K40, to ensure regular connection. (Has been mentioned above, by curro101)
And any tests that confirm anything to be OK, when the car has driven in and out of the test location, just confirms it is working at the time; you appear to have an intermittent fault that has happened about five times in quite a few months, so they'd have to be lucky to catch it.
Key points; the failure is "absolute" and kills the engine (so lasts for some time) but can be undone by restarting, immediately.
Most examples are during tick-over (so might be short) but it has happened during normal running.
No mis-fires have been noticed during normal driving; if it fails, it stops the car.
Some issues have been noted during tick-over and the transition to on-power, but this has improved with Techron cleaning. (This might be a different issue, and hopefully has now been cured with a clean-up)
One other thing that might benefit the analysis is to clean the MAF sensor, so that we can remove any pollution (oil) problems there from the consideration.
If it happens when driving, try to notice if the power is cut off sharply (electrical), or if it rolls off (fuel starvation); it may not be possible to detect that, but worth checking. (It is obvious on a carburettor car, but fuel injection doesn't have much of a reservoir of pressure.)