Tom
The redesign at North Berwick would likely be referring to the Burgh course, sometimes known as the east course and what is now known as the Glen. Like an awful lot of courses it started as a nine holer which Ben Sayers laid out in 1906 (?) and was eventually extended to 18 holes sometime just before or after the war (I think from memory).
The Council decided to tart up the course with the intent of making it more attractive to visitors and approached Robert Maxwell for advice. Maxwell was a member of HCEG and the Tantallon club (I think), had won the Amateur championship on a couple of occasions and had got Colt involved and indeed claimed to have assisted in redesigning Murfield at around about that time. Maxwell suggested Colt, and Colt provided a fee proposal. In good old Scottish Council fashion, the Council then decided that they wanted a competitive quote and MacKenzie was asked to put forward a proposal which he did.
MacKenzie won the commission based on his price and he duly provided a design. Unfortunately I only have the hole yardages and neither do I have a plan of the course before (or indeed immediately after) so it is difficult to know whether they followed his design but they did redo the course. I assume therefore GI was referring to this work although equally there might have been work ongoing at the West course then.
Niall