Sir – I was walking through Radcliffe Square on Friday, November 13, and passed a group of no more than six people holding a banner protesting peacefully about the need for climate change.

As I walked on I noticed with amazement the group were being watched and photographed by two police officers and one community support officer!

I wonder on what basis these officers were deployed, how much the deployment cost the public purse, and what happens to the photographs.

Jeremy Burrows, Oxford