Ally
Cairnes was friendly with many of the top British amateurs of the period, including Colt, and HSC may have had some influence, but Cairnes was a very active and well respected designer in his own right. I know Darwin (another top amateur) gave him full credit. I didn't know Morrison was responsible for the 8th, 9th and 18th holes. What year was that?
I'm not certain who is responsible for the Klondyke, but I do know it existed as earlier as 1902, so it is prior to Charles Gibson's redesign.