Hi Miss Alison :0)

T here is my reply
You may have a strong case here - but how could the people reckon market day? or brewing time ( a favorite celtic sport ) or anything else if they had no common calendar?

Celtic Aristocrat ?, I've no idea what you mean here. The last remaining traces of the warrior society that existed is in Scotland. Again these were a mercenary wandering people not settled people like say your Galatians etc,. So you'd be wasting your time looking for the origins of the 'celtic' calendar there except at Negrange where a use of it exists. Click here Newgrange 3000 BC

More Silly Halloween stuff
During insecure times the Crown (the King and/or Queen of ...in this case merry England) kept a piece of rock called the 'Stone of Scone' a prisioner in the Tower of London. Please do laugh as much as you like ...I did when first I read about this. The rock had been used in royal ceremonies by the Scots before the act of union etc., After that time it was taken to London to prevent the Scots crowning their own monarch. (My two cents I would crown em all with any old rock)