According to Larry Hatfield, the serial # system changed around 1960 or '61 I believe. Prior to that, the first number identified the bowyer...and I believe Mr. Howatt used # 1.
In the early 60's, the process became assembly-line type as several workers performed a different funtion on each bow.
(I also agree that the "S" is a mystery unless bow is a Howatt Hi-Speed in 62" which would be rare, huh?
I wish Mr. echo62 would give us some pics too.