I looked on Velobase and thought that might be the one as it was almost the same, but there is a slight difference in that the rear of the parallelogram body is black plastic, without any model identification marks, whereas the Velobase one has all metal. I'm not sure how much difference that makes.
Must admit I'd not noticed that
There must be loads of variations on these probably depending on what parts Simplex had in stock. The parts must be dimensionally interchangeable between models. The back plate looks a bit like one from the later version of the Prestige which had the Delrin sandwiched by steel becase the early all-Delrin ones broke.
Guess how I know that.......................
Today is the yesterday of tomorrow.