WW2Buff, thanks for the response, I don't think I took your query the wrong way, hope my words didn't convey otherwise. The vagaries of wartime production and components leads me to be a little broader in acceptance of variations than some may choose to be. Your comment was taken as being curious, as I am about the cocking piece. Can't offer a definitive hypothesis as to why it's the Mark 1 type, but think it's unlikely to be a No 1 Mk III or III* component.

Perhaps some one will have better info to enlighten us both? Anyone out there...?