In reply to Wiley Coyote:
I did wonder about that.
The standard translation of 'Bothy' to welsh is the usual Welsh word for a cottage "Bwthin", but the structure otherwise would be right for something like "Cymdeithas Llety Mynydd" (LL counts as a single letter in Welsh so would be C.Ll.M.) which would loosely translate as "Mountain Accomodation Society".
Can't find this usage online though.