Calder Mackay were somehow related to the Farmers Trading Co in Auckland
Farmers took them over about 1970-ish. Photo looks to be about early 1950's - see the early Hillman Minx across the road. Who are the guys in uniform? St Johns or Boys' Brigade??
And the tractor pilot looks like a Zambuck of old...you know, the ones who used to run onto a rugby field and treat any given injury with cold water...