The chairman of the Oxford group of the Institute of Advanced Motorists seemed to miss the point when complaining on Saturday’s front page that the average speed in the new 20mph zones has hardly changed.

The average speed that motorists travel safely within the zones is not important because only a small fraction of motorists are a constant danger.

A better measure of the success of the zones would be whether the speed of the fastest drivers has dropped from reckless to safer levels.

Geoff Broughton, Knollys Close, Abingdon