As far as I am aware, Japanese spec Minis have no alarm system fitted. I know nothing about 5AS so looked it up on the Interweb and there is no box in Pam's Mini that looks like that portrayed on the pages I saw, there is no fuse for any alarm, and the car doesn't have fob access - just a key.
So, I would say that you are correct in that it doesn't have it fitted.