Bob:
Paul Turner should certainly be considered Golfclubatlas's expert of Harry Colt (and the rest of the English so-called Heathland architects).
Right off the bat, it's probably a little difficult for Americans who don't have a real interest and knowledge in European architecture and it's architectural beginnings, in the sense that we think of golf course architecture, to fully understand an architect such as Colt and all that he may have meant to the world of golf architecture, its earlier years and most definitely its evolution.
All this is made even more difficult, in my opinion, by the nature of Colt's company and how exactly he worked with (or didn't work with) his partners--notably Alison, Mackenzie, Morrison and Harris.
If one looks at Colt's career inventory in something like Cornish & Whitten one sees and awful lot of golf courses under Colt's name--a dozen or more quite well known in the world of golf and many more in Europe and the United States that are well known and respected by some but not that well known generally.
But the thing that makes evaluating Colt specifically a difficult thing to do, at least in Cornish and Whitten, is how intertwined in attribution many courses are with Alison, for instance, partiuclarly in the US.
Because of that it seems almost impossible to ever determine exactly what Colt did and what Alison did. Many courses in the US, for instance, are attributed well into the 1920s and 1930s to both of them together but it appears, to me anyway, that Colt may never have returned again to the US following his well-known visit to PVGC and Canada in 1913.
I've asked and asked anyone, including Paul Turner, to come up with some evidence that Colt did return to the US after 1913 but so far no one seems to have been able to find any evidence of that. It's fairly well known, I guess, that Colt was not that fond of traveling.
But if Colt never did return to the US, for instance, that sort of puts a whole different perspective on the career inventory that's attributable to him, certainly in conjunction with Hugh Alison. Cornish and Whitten even mentioned in his bio in their book that Colt was opposed to mail-in designs so if that was true and he never returned to the US one should certainly draw some interesting conclusion from that about much of what Colt actually did do.
Nevertheless, and, certainly in my opinion, the work that is definitely known to be Colt exclusively does show an absolutely amazing degree of sophistication in design and at a very early time. That, to me, puts Colt but perhaps also those other architects known as the "Heathland architects" very high on the list of overall importance in the history of golf architecture.
But frankly, from everything I've seen from him I'm inclined to put Hugh Alison at probably the same level or perhaps even higher than Colt himself. It just so happens that Colt was Alison's senior in architecture and Colt was the one who brought Alison along in the company. But Alison did some amazing work in the Far East, perhaps elsewhere, and certainly in the US. It's no secret at all that Alison spent a great deal of time in America--his name pops up all over the place in some of the research Wayne Morrison and I are doing on Flynn et al, for instance!
But again, if Colt never returned to America after 1913 how can anyone seriously give him the credit that his career inventory seems to suggest? To me most if not all of the work in the US must go to Alison almost exclusively if Colt was not here when all that attributed "Colt/Alison" work was done over here.
The so-called "Heathland architects", again, should not be overlooked or underestimated as to their importance in the way of various "influences" on architect and certainly in America in some areas. It seems like the "Heathland architects", certainly Colt and Alison were sort of the "go to guys" for some significant American creations and those that did them such as Crump, Wilson, Fownes, and perhaps even some like Perry Maxwell or Robert Hunter or Max Behr.
The work of Colt and that of Mackenzie, who nominally were partners should never be remotely intermingled, in my opinion, with the notable exception of perhaps Alwoodley, an early and really significant course in the evolution of architecture, in my book. They apparently didn't get along very well later and there is good evidence that they created a partnerhip as much for "defensive reasons" as anything else (so they wouldn't have to compete against each other business-wise!)
Colt was significant, in my opinion, in the history of architecture but exactly how significant seems to remain pretty elusive. I personally wouldn't call him the greatest of all time, not yet anyway, but from what I do know of him certainly in that top handful. Perhaps when more becomes known about him that will go up but it could also go down.
And in that vein, I'll ask anyone who might know, including Paul Turner, did Colt return to the US following 1913 or didn't he? I'm looking of course for real evidence of that in a working architectural sense and not speculation. Because if he never did return that certainly is important to know.
(Wayne and I do have a letter from Hugh Wilson were he quotes a letter from Colt to him in the early 1920s asking for agronomic advice and resource where Colt mentions that he has not seen Wilson in well over ten years and does he remember him? With all that was going on around Philadelphia and the East coast architecturally at that time that sure seems to imply that Colt probably never did return to the US following 1913. All those architects were a relatively tight fraternity at that time and it sure is obvious (and documented) that throughout that entire time (teens into the 1930s) Alison was all over the place over here and very visible too).
I know a little more about Alison (more than Colt) and his work, his philosophy, his writing, drawing, recommendations and architectural analyses by him and to me he is one of the most significant architects I know of in the history of golf architecture. His work at a quite early time showed amazing sophistication in every way!
But I think the thing to focus on most is not just Colt alone but on the entire group that was known as the early "Heathland architects". In a sense they are the ones that first brought golf architecture out of the linksland, and out of a period of real "dark ages" outside the linksland to what became some amazing sophistication in early golf architecture!