The problem is that modern batteries last well but seem to go without warning. Either that or the voltage hits a certain level and it all closes down.
The Morgan dealer isn't going to come out in the middle of the night to the middle of nowhere. Likewise a breakdown agency isn't going to get the battery out without knowing how to get at it. Hence referring to your dealer is as much good as a 'fart in a spacesuit' ( TM saying)