Smit said: "I am delighted to have signed for a club widely renowned for the ferocious work ethic and spirit on the field and for the unique way it treats people off the field. It is becoming a very special rugby club, combining a cast-iron commitment to develop young English players with a clear South African flavour. I'm looking forward to rejoining former teammates like Deon Carstens and Brad Barritt, and also to working with players like Jamie George, last year's England under-20 hooker."
Mark McCall, Director of Rugby, said: "We are absolutely thrilled to have signed one of the most prominent and admired players in world rugby. John is an outstanding leader and hooker."