Its three years.
The Termi system should pass the MOT as long as it has'nt got 'not for road use' or similar stamped on there.Early cans had nothing stamped on them,so should pass.Later cans are marked underneath near the rear light cable tube.:(

Just to confirm the comments above, I had my Termi'd 749 MOT'd yesterday without any problems. In fact, everybody there said it sounds the dog's wotsits!!! :cool: