http://www.express.co.uk/news/uk/434...aiming-at-cars
Apparently the fact that SAS snipers occasionally lay on bridges over roads and aim at cars is evidence that they were complicit in the killing of Diana and nothing at all to do with practicing in case they actually do need to stop a car containing terrorists driving at high speed along a motorway.
Either that, or they have the best snipers with the best weaponry in the world and they actually can hit a car in a tunnel in Paris with a bullet shot from Wales.