They said that the "organisers" have "invited" the police to the service, but not "notified" them. Apparently Scotland Yard are "aware" of the carol service, and the Home Office said that the law applies to "protests". "The exact status of a carol service isn't clear" apparently.

No arrests reported, and there was a nice rendition of "The first noel" going on in the background.

The reporter gave a brief overview of the law under which unauthorised protests around parliament count as a Serious Organised Crime, mentioning Maya Evans' recent conviction for naming the dead outside parliament, but not mentioning Brian Haw's onging (and still legal) protest which was the original reason for the law.

 http://www.bbc.co.uk/radio4/news/ram/news_6pm.ram - scroll to about 21 minutes into the programme, but be quick because it'll be gone in 24 hours!