Hi Keith,  We too have recently purchased a 9" Britannia.  Ours is
the "Alexandra" model "Smoking Cabinet".  Reg. No. 370.254 marked on
the inside wall of the cabinet.  We have just begun to research this
and found the most information in "The Music Box Makers", "The History
of Music Box in Sainte-Croix", by Jean-Claude Piguet (copyright April
1996), English Translation (ISBN 0-9759882-0-4).

We have not yet found serial number production dates; on the contrary,
many of Britannia's founder Barnett H. Abrahams early boxes are marked
"BHA".  In any case, the time frame for the disc boxes was 1890-1900
due to the decline in the quality of the large cylinder boxes.
Abrahams boxes were considered the best sounding of the "Loud Boxes".
Does anyone else have any more info for us?

Wayne Myers