Sir - Those in positions of public responsibility could be expected to obey the rules, even traffic regulations but this is not always the case.

On a recent Sunday evening, the Commissioner of the Metropolitan Police, Sir Ian Blair, gave the sermon at evensong in Merton College, but outside, in Merton Street, his large car, with bodyguard, was parked on double yellow lines.

Last week, the Lord Mayor's car was parked on double yellow lines in Cardigan Street, in Jericho.

Such prominent figures should set an example to encourage the rest of us to obey the rules.

A. Hornby, Oxford