Sir – On an idyllic Saturday afternoon we were strolling down Broad Street with two friends visiting us from the other side of the world. Outside the Sheldonian there was a small, impeccably-behaved animal rights protest.

On our side of the street, two policemen armed with cameras and huge telephoto lenses were taking photos of anyone who joined the protestors. When I asked them why, they said “for intelligence purposes”.

How do I explain to our foreign friends that, in our great democracy, just crossing the street to join a peaceful demonstration would now be enough to put their faces on a police intelligence database?

The first time I witnessed this practice was in East Germany in the 1980s. Then I found it intimidating and very unBritish. Now, in Oxford in 2009, we accept it as quite routine.

Jon Barton Watlington