AN UPDATE!!
I find there's nothing more frustrating than searching out a thread through forums either directly or through Googling that highlights exactly the fault you're encountering only for the final outcome / fix never to complete the story, so here I am, back with a continuation of the story!
It seems the learning curve from understanding the quirks, foibles and engineering from my passion for 60's > 90's Citroen models to the delights of maintaining a P38 still didn't fully prepare me for the frustrations I have encountered since buying N151 SDW in November but as always, it's all about getting the right reference / facts and making the correct informed decsions! For that, first I must thank all the contributors that have given their advice previously in this thread especially Mozz.
The fix?
I bit the bullet and purchased a new plip from LR and in the process confirmed the EKA - this was a weird one as the previous owner had managed to mix the code up BUT as the wrong code first used x4 key turns in the door lock at the off they were actually clearing the BECM to accept the remaining code that by fluke worked with the following key turns! This all went south though when attempting to add an ADDITIONAL x4 key turns first!!
First lesson learned:
they're actually not a bad bunch at the local LR dealers and they're genuinely helpful - more importantly, they confirmed the EKA and helped advise the procedure to keying it in.
Second lesson learned:
not to get bogged down assuming all sorts of wild things were kicking off with the alarm immobiliser before calmly sorting through the facts and applying basic car stuff knowledge - it seemed too easy to miss the obvious and speculate all sorts of crazy things were a fault of the evil BECM. I discovered only after establishing an accurate reference point with the EKA and new plip that there was still a starting issue that was no more complex than a slightly sticking starter motor!!
The car had previously sat for almost x2 years due to the failing health of the previous owner and basically the starter needed regular use - it hasn't missed a beat since.
Third BIG lesson learned:
with the constant PITA of flat batteries and EKA with key lockout thrown in along the way for good measure was the purchase of a Generation 3 rf receiver! The car has gone from being possibly the most unreliable starter to (almost) a normal car now! In an almost surreal like experience, I can now walk up to the beast and from a good distance plip the car unlocked and wonder of wonder, the battery still has life to open doors and start the engine. This experience may actually catch on...
It seems like an obscene amount of money, even secondhand, is being fleeced for the purchase of around 20 quid's worth of Asian PCB but if there is one thing that has been a revelation in my short ownership of this P38, it's this as it works and is so worth the outlay. I baulked at first wanting to devote monies instead to other areas on the car that would respond well to some TLC but that would all be for nothing if the car won't start!
So. It lives. To get it up and running with an MOT I now need to make sense of the SRS warning and find out if it does actually work on the LPG system fitted! I'll open a new thread elsewhere then!
And.