At lunchtime while I queued to buy a sandwich in a supermarket I saw a crowd of teenage boys gathered around the window with a mobile phone pressed against the glass – they were clearly filming me. The same thing has happened several times before. By the time I’d bought my lunch the boys had gone, and I walked back to work feeling uneasy. Worrying about being filmed in public and appearing on You Tube unexpectedly isn’t something that everybody has to think about.