I got done for my front right blinker not working and it was just a "go home, fit new bulb and post off the paperwork to say i've done it" and the transport guy also added "don't send the papers today, do it either tomorrow or the next day. Otherwise it'll look suss."
What was the drivers attitude to the cop ? Could of had a bearing on why the cop turned around told the driver to get the car epa tested.