There are instances of other Morgan models discharging batteries more quickly than you might expect when the car is not being used.
In your shoes, I would start by measuring the battery voltage - which you should be able to do at the starter motor. No idea where they put the battery on a late model 4 seater, but if its not under the bonnet, you could start by looking under the rear seats.
Hopefully someone who knows 4 seaters will be along in a minute.
