Mark_x11,
From my collection of Atco brochures and associated paraphernalia it would appear that production of the Suffolk engined Atcos commenced in (or about) 1964. All of the other materials that I have show the Atco range being fitted with Villiers engines prior to 1964. It is noted however that the 1964 Atco 20" HD model remained Villiers powered.
Cheers,
Sir_Chook
