It was added by a previous owner, woll never know whyI've never seen a clip-on holder from Gillette, that combined with the absence of any Gillette branding; instead the name 'Terry', suggests that Gillette are not the manufacturer
It was rivettedIt is a Terry Clip. How is it attached to the blade holder? Weld?
Could be, never thought of thatI have had quite literally thousands of razors through my hands (ouch!) ... I jest ... I am pretty sure I've had a Gillette with this configuration with a clipped holder and nickel case. Given the proliferation of Gentleman's Sets I think it's just an aftermarket put-togther and could well have had a Souplex or Wardonia razor as a Gillette.