Rule 137
On a two-lane dual carriageway you should stay in the left-hand lane. Use the right-hand lane for overtaking or turning right. After overtaking, move back to the left-hand lane when it is safe to do so.
SteerTogether · Official English reference
Read rule 137
General driving rules: rules 103–158
Study signals, vehicle control, speed, stopping distances, lane markings and attention while driving.
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