Ah, OK, that is all really useful info, particularly the bit about waking the BECM. I have the photo that was posted a while ago with pictures of the Mk1, 2, 3 and will use that. Given the potential for an error message that requires a key fob press, it makes sense to be able to comply...
Looking on eBay, seems that units are marked with little coloured stickers:
No dot: Mk1, avoid.
Blue dot: Mk2 with metal shield, avoid
Green dot: Mk3, also identified by price of around £200 used, and £260+ new, this is the one to get.
I hope that is correct, please let me know...
Oops, drifted off subject (trim clips) but as ever in this Forum, have learnt more about my P38 and its typically Landy "features" (idiosyncrasies). Thanks guys.