When may you overtake another vehicle by passing on its left-hand side?

Explanation: You should normally overtake on the right, but there are some occasions when you may overtake on the left. These include when you're driving on a dual carriageway or motorway and the traffic is moving slowly in queues, or when a vehicle ahead is positioned to turn right and there's room to pass on the left. On dual carriageways or motorways, don't overtake on the left if traffic is flowing freely.

Category: Band 1 road procedure

References: The Official DVSA Guide to Driving: Section 7, Highway Code: Rule 163