AsTarpen flex drive unit. Would have had many uses, eg hedge trimmer, lawn edger, or even chainsaw!
An earlier one of these was seen working with various attachments at the 2015 Three Cocks Rally
Later Tarpen Generating plant, fitted with Villiers F15 engine:
Villiers F15 Manual, as found in some 1970’s Tarpen GeneratorsVilliersF15Manual