At what point should drivers start indicating their intention to leave the motorway?

Drivers should start indicating their intention to leave the motorway at the 300-yard marker. This is important for several reasons. First, the 300-yard marker provides sufficient time for other road users to react to the driver's intention to change lanes and exit the motorway safely. It allows adequate distance for the driver to check mirrors and blind spots, adjust their speed if necessary, and maneuver into the appropriate lane well before the exit.

Furthermore, signaling at this point helps maintain the smooth flow of traffic. It acts as a notification not just to drivers around you, but also reinforces good driving practices. Proper signaling enables other drivers to anticipate the exit, allowing them to adjust their behavior accordingly, which ultimately enhances safety on the road.

Choosing a point that is too close to the exit, like the 100-yard marker, may not provide enough time for drivers behind to adjust, creating a riskier situation. Thus, using the 300-yard marker as a guide strikes a balance between fighting the congestion of the motorway and ensuring safety for everyone involved.