Finally the saga is over and the problem fixed for good.

After amassing a collection of BEM's and ignition switches and not being able to successfully learn the smartlock codes between any of the ignition switches and BEM's I decided to track down an already matching BEM and ignition switch from a donor car.

So last weekend I headed off to my local Pick a Part wrecker to see what I could find.
After looking through numerous EF's and finding either the BEM's had been removed or the BEM's where not the "Blue" one that I was after.
Finaly after looking at the second last EF on the site it had the combination of blue BEM and ignition switch, the only problem was no keys for the ignition switch.
So I removed the BEM and ignition switch from the EF II Sapphire donor car.
I took the ignition switch to a local locksmith who re-keyed the tumbler to fit my existing tibbe key.

Afetr getting the ignition switch back from the locksmith I fitted it to the car along with the matching BEM ... turned the key ... and the engine started!

It's been a week now and the and the car has started every time including on very hot days which would have otherwise seen it fail to start.

Very happy to finally have this sorted out and have a reliable car again!