Duncan, could the holes be brought back to life easily?
It depends what you mean by 'easily'!
Several of the old fairways are maintained by the club as practice areas, but the holes that everyone remembers most fondly have been subsumed by woodland.
The most famous hole was the short 17th which played across the entrance road, over a stream, and up to a tiny green almost invisible in a clearing in the trees high above one's head. The tee remains, but all other vestiges of this fine hole have gone. Nearly 40 years after playing it regularly as a kid, I can still remember that shot and the aprehension one felt addressing the ball. You either hit the green or re-loaded. I never played the course competitively but can only imagine the psychological effect of such a hole so late in the round!
There seems little will within the club to reclaim or even acknowledge the old holes. The land is now owned by the government and the membership appears perfectly happy and very proud of their mis-mash course which now features multiple water hazards complete with fountains.
It doesn't stop them setting great store by their 'MacKenzie heritage' though...
... Dr Mac is the only architect mentioned in the club history on their website.
http://www.hazelgrovegolfclub.com/our-course/club-history/Interestingly though, it says that the course was constructed by Mackenzie & Nicholson Contractors in the early 1920s. My suspicions are aroused. Could it be that the course was actually the work of MacKenzie's brother and that the good doctor had no involvement at all?