'Section 89(2) of 1984 Road Traffic Regulation Act requires that a person prosecuted for driving a motor vehicle at a speed exceeding the limit shall not be convicted solely on the evidence of one witness'

This basically requires there to be corroboration. Corroboration can be provided by the equipment in a police vehicle or by Vascar or similar speed measuring equipment. Alternatively two police officers may provide sufficient evidence in a case of speeding. However, it is important to show that both officers saw the same vehicle at exactly the same time.

I.e You can relax, you are safe mate. Sounds like he was just winding you up - probably because you were gobby.