Tubby,
Here's what I found on my Pearsons. Even my Sovereigns have the Cat #, 1097, 1094, etc. It seems that most of the bows after 1958 have a serial number that starts with the last 2 digits of the Cat #. My Hunter, Cat # 709, has an S.N. that begins with 09-XXXX. My oldest Mercury Hunter, Cat # 1096, has the S.N. beginning with 96-XXXX. 1958 was the first year that BP's had names, prior to this they had only Cat #'s. In 1968, a 0 (zero) was added to the end of the Cat #-my Hunter became a 7090. Early on, the length was shown as 5'6", 5'4", etc. Eventually they changed it (I'm not sure when), to inches, after 1958 for sure. I have a Safari that is listed as 5'6", they were only made in '58 and '59.
Hope this helps.
Phil