Hi Nige
Only going by a little snippet I read many years ago but I think you'll find that the word fall is the original English word for autumn. It was used in Elizabethan times (ish) and maybe before. I guess it comes from falling leaves.
English settlers took the word over the pond where it's still used today. The Americans, therefore, are using authentic English. Not sure when the word Autumn gained prominence over here.
So there you have it....I'm a mine of useless info. Either that or what I read was a load of bollocks.
Best regards to you & Moley
- Dermot