Sean,
There are many, many Golden Age courses where we don't know exactly which architects designed what features. I think it is impossible to rule at an architect as a designer of a certain golf course because we don't what exactly he did at said golf course. We wouldn't have any architects left to credit!
At Addington, we don't know how much of the course is Abercromby's work, even though we are sure he designed much of the final layout. We are also pretty sure that Colt had a hand in the final design. What exactly did he do? Unknown. However, we need to keep his name on the list of credits and find out roughly what he did at Addington.
All,
Sorry for the misspelled title. I swear, Abercromby and Abercomby looked identical to me!