Rule 151
In slow-moving traffic. You should
- reduce the distance between you and the vehicle ahead to maintain traffic flow
- never get so close to the vehicle in front that you cannot stop safely
- leave enough space to be able to manoeuvre if the vehicle in front breaks down or an emergency vehicle needs to get past
- not change lanes to the left to overtake
- allow access into and from side roads, as blocking these will add to congestion
- be aware of cyclists and motorcyclists who may be passing on either side.
To read more about the Highway Code Click Here