Sir – I am writing to express my concern about the behaviour of the police which I witnessed on a visit to Oxford last week. On the morning of July 19, a friend and I were walking past an Oxfam shop when we saw three policemen holding a man face down on the street. One was twisting his arms and another was clasping his face. We shouted at the police, telling them to stop but they ignored us. Presumably this is standard behaviour. Tourists were assembling for a guided walk and a man stopped to film them, but they continued for several minutes. If police behave like that in public, how do they behave at the police station?

Julie Boston Bristol