I have a 2018 +4 which came with three keys one of which I keep in a safe place.
As mentioned elsewhere the transponder in the key reacts with a wire loop around the lock. This wire loop connects into a black box up behind the dash that has been specially made for Morgan by Avonwood Developments Ltd:
![[Linked Image]](https://www.tm-img.com/images/2020/08/16/Avonwood.jpg)
This in turn connects to the ECU
So I think the answer is it is bespoke.
I have not asked my dealer but they may be able to program a new key