I'd go with the idea of the Telmarines and the Old Narnians using different calendars. The Telmarines are supposed to be from Earth. I'm not sure that canon nails down the timing of their departure from Earth, but it has to be after The Magician's Nephew, so them using some version of the Gregorian calendar would make sense.
(no subject)
Date: 2016-07-03 02:28 am (UTC)