You are much more likely to be killed if you are hit by a car travelling at 30mph than at 20mph. Slower speeds mean fewer lost lives.

But the benefits of the coming borough-wide 20mph speed limit don’t rest on some naïve belief that all drivers will suddenly stick religiously to 20mph once the new limit is introduced.

This is part of a gradual culture change in favour of more pleasant neighbourhoods less dominated by speeding traffic, where pedestrians feel safer crossing the road.

The council will monitor the impact of the 20mph limit closely and liaise with the police. Only the police can enforce speed limits so there will be no revenue stream for the council in fines.

We’ve seen big rises in cycling in recent years, and the new limit is about encouraging more people to cycle and walk.

There is no evidence that speed limits have much impact on the air pollution, if anything a 20mph limit will be helpful if it smooths traffic flow.