Sir – I was delighted to read in the letter from Pierre Marshall (Letters, May 8) that a police constable has been seen enforcing the law on riding bicycles across pedestrian crossings in Summertown.

The crossing by the Co-op and Lloyds TSB is a busy one, with narrow pavements on either side. I expect that cyclists would be wishing to cross diagonally whilst pedestrians would be crossing straight across. As such I suggest that it would not be sensible or safe to convert it to a Toucan crossing where cyclists are allowed to ride across with the pedestrians.

The constable was enforcing the law, helping to preserve the safety of pedestrians and cyclists alike and teaching the school pupils, your correspondent mentions, a valuable lesson.

The lesson: that one can’t always do the thing that is most personally convenient; one has to think of others. That could be the most valuable lesson they learn that day.

Vernon Porter, Oxford