In Graham Priest's book there is an engineering drawing of what appears, to me, to be suggested to be a Mk2 Sten Bayonet. It would appear to be a complete redesign with the blade now a tube which would fit over the barrel and angled off to a point at the business end. There would have to be some kind of catch mechanism to lock it to the barrel or shroud? If my understanding of the text relating to this drawing is correct the Mk2 Sten Bayonet didn't progress any further than the drawing board, i.e. none were actually made.