A. When there are lane closures
If you're towing a caravan or trailer, you mustn't use the right-hand lane of a motorway with three or more lanes except in certain specified circumstances, such as when lanes are closed.
A. 30 mph
Travelling at the national speed limit doesn’t allow you to hog the right-hand lane. Always use the left-hand lane whenever possible. When leaving a motorway, get into the left-hand lane well before your exit. Reduce your speed on the slip road and look out for sharp bends or curves and traffic queuing at roundabouts.
Large, slow-moving vehicles can hinder the progress of other traffic. On a steep gradient, an extra crawler lane may be provided for slow-moving vehicles to allow faster-moving traffic to flow more easily.
Never overtake on the left, unless the traffic is moving in queues and the queue on your right is moving more slowly than the one you’re in.
A. 40 mph
If you’re towing a small, light trailer, it won’t reduce your vehicle’s performance by very much and it may not be visible in your mirrors. However, strong winds or buffeting from large vehicles might cause the trailer to snake from side to side.