The Battle of Lincoln's Inn Fields

I was a little early (unusual for me!) arriving at work today, so I had a quick stroll in Lincoln's Inn Fields. I spotted a 'battle' going on in the bandstand. No blood was shed.

I'm not exactly sure what they were doing, but I'm always fascinated when I see people doing martial arts/tai chi etc. in the parks. I'd be rather embarrassed if it was me (especially if there were people like me lurking around taking photos to blip!)