To join the flow of traffic, is it permitted to reverse more than fifteen metres?

As a general rule, reversing is prohibited, except in the following cases on an exceptional basis and always covering the minimum distance strictly necessary: 1. As a complementary manoeuvre when stopping, parking or joining the flow of traffic. In this case, the reversing distance must not exceed 15 metres or encroach on a road junction. 2. When it is not possible to move forward or to change direction or sense of travel. In this case there is no limit on the reversing distance, and it may even encroach on a road junction if necessary. Reversing is prohibited on dual carriageways and motorways.