The first ATCOs were American imports from the late 1970s to 1986 and included several model numbers including 11/36 and 11/36E.

They were, I believe, Dynamarks, as were the first Westwoods. Two UK brands that used those US manufactured machines to kick start their ride-on offering. We serviced both the US and UK built Atcos and both left a fair bit to be desired – particularly Atco’s effort to build a power driven sweeper/ collector.
At one point Atco were owned by Blur Circle (yes, the cement company) and one of their directors was a customer running their latest offering on his country estate and I had to be uncharacteristically diplomatic about his “ heap of ****” . However, we did manage to replace it with a Cub Cadet and they still run a Cub to this day.