Sir – The introduction of 20mph speed limits in areas of London has contributed towards a 50 per cent reduction in the number of children killed or seriously injured on the roads.

Research published online in the British Medical Journal examined casualty rates between 1986 and 2006 and found that in spite of a steady decline in the number of road casualties in London, the additional effect of the 20 mph zones was a reduction in casualties and collisions by an amount that has taken over 20 years to achieve on roads without them.

The county council is to be congratulated on following London’s lead and making Oxford city a safer place.

Nick Lee, Oxford