Sir - Assuming that they have evidence of accidents caused by driving at 30mph, supporters of the 20mph limit are surely being too timid. If road safety is their aim, why not make it 5mph with someone in front waving a flag?

Would they also like to give their budget for new signs, in prominent positions, cluttering up the streets? Then they could say how the new limits are to be enforced. Are we to have a rash of ugly Gatso cameras all over the inner streets, or do they expect the police to provide speed traps?

There is no point in having laws that cannot be enforced.

Most drivers know that the familiar 30mph limit is the maximum, and if conditions dictate, as they usually do in the centre, they go slower.

They can assess 30mph without looking at the speedometer, but 20mph will have them taking their eyes off the road constantly.

If they are in a cluster of the most lawless and unpredictable road users, the cyclists, they want to get clear of them. 20mph will have most cars in fuel-guzzling, exhaust-emitting low gears. It is yet another proposal from the anti-car lobby that does not stand examination.

Bill Leonard, Oxford