The left-hand lane on a three-lane motorway is for use by

Explanation: On a motorway all traffic should use the left-hand lane unless overtaking. Use the centre or right-hand lanes if you need to overtake. If you're overtaking a number of slower vehicles move back to the left-hand lane when you're safely past. Check your mirrors frequently and don't stay in the middle or right-hand lane if the left-hand lane is free

Category: Motorway Rules

References: The Official DVSA Guide to Driving: Section 11