I read somewhere that the "Bisley" mods to the Colt SAA were to accomodate the shooting style required at the shooting matches in Bisley, England. I can't find the article, though.
The Bisley-style grip frame has visually more curve and the hammer spur is lower than the standard model. As I recall the article, Colt did that so the gun would point naturally when it was fired with the Bisley-required bent elbow instead of the straight elbow American shooting style.
Can anyone confirm?

Yep, you're correct. In "The Colt Heritage," by R.L.Wilson, he writes that the Bisley was inspired by the Flattop Target Model. Origin of the name was the site in England where the British held their major competitive matches.

Bisleys joined Colt's lineup in 1884 in both standard frame Bisleys and the Flattop Target Model. Approximately 44,350 Bisley standard frames and 976 Flattop Target pistols were made.


L.W.