I am not aware of any proximity capability of the BMW/Morgan system unlike cars with keyless go/start. I would doubt this could be the issue.
My S2 had a trapped wire in the engine bay which was causing a consistent drain which a specialist electrician isolated and replaced. It was pretty good after that and would do a couple of weeks without a charge. It had no alarm and a Becker which retained memories. I was using the banner red bull back then. It did not have a tracker. The boot lamp is always lightly on even when parked and locked.
The Coupe does have the mother of all trackers and has never been able to do more than about 2-3 days without a drive or boost/trickle. Various lights have a mind of their own.
I still love it. Just like the wife loves a defective me. A little.
