I was thinking that brochure had to be older, the Hd8 was phased out by 1976, 1971 was the companies change to yellow with the redesign of the frame and the introduction of the Fuji Engine (pictured).
The other Brochure you have dated 1971, as far as the Greenfield goes has to be at the latest a 1969 model. Last of the red machines with the old front axle but with the bigger G65 Engine.
To my knowedge that partnership must have only lasted 2-3 years, and must have only been for the southern Dealers.
I might be Biased, but as far as 1970's mowers went, Rover had to be the on the top. Especially by the mid 70's when they had the High arch Regal and Baron models. Chrome metal ball bearing wheels, now proven one of the toughest alloy bases of the time, Huge catchers and some of the biggest engines of the time, the Regal with the factory 5hp briggs is a beast of a machine!