Ministry of Transport and Civil Aviation and the Central Office of Information

“ DO NOT OVERTAKE ON THE LEFT.
17 Before pulling out to your right into a traffic lane carrying faster moving traffic, watch out for and GIVE WAY TO TRAFFIC IN LANES TO YOUR RIGHT. USE YOUR MIRROR to make sure that the lane you will be joining is clear for a long distance behind, and bear in mind that an overtaking vehicle may be travelling much faster than you are. Give a clear signal of your intention WELL BEFORE you change from one lane to another. ”

“ The outer (right-hand) lane is for overtaking only; do not stay in it longer than is necessary after overtaking vehicles in the centre lane.
15 DO NOT DRIVE TOO CLOSE TO THE VEHICLE AHEAD OF YOU IN YOUR LANE; allow at least one vehicle length between your vehicle and the one ahead of you for every ten miles per hour of your speed, and more at night or in rain or snow.
Overtaking
16 OVERTAKE ONLY ON THE RIGHT. Right-hand lanes will be
free from slow moving and right-turning vehicles, obviating the need for overtaking on the left. ”