Google Maps - what are all those people doing in Trafalgar Square?

I know Trafalgar Square is busy most of the time, but that is quite a crowd. It’s spilling out into the street near the church of St Martin-in-the-Field. And there appears to be a red carpet at the foot Nelson’s Column. Looks like winter judging by the long shadows and lack of leaves on trees. Any idea what the occasion was?

There was no shortage of public festivals in the square while Ken was mayor, so there’s plenty of occasions it could be.
This page has a photo of the 2007 Chinese New Year celebrations in the square, very obviously with the same layout of stage, TV screen and tent. But that’s the standard kit for one of those events, so this doesn’t particularly narrow it down.

On the other hand, if you scroll north to Chinatown itself, you can clearly see zig-zag rows of lanterns above the streets. I can’t remember whether they’re there all the time, but this photo of Gerrard Street suggests that they aren’t. There are however plenty of photos out there showing them up during the New Year festivities.

The obvious question in the Google image is why is the crowd being kept back from the space between the fountains in front of the stage?

Ah ha! Googling Google+maps+Trafalger+Chinese gives hits, with this as the first.

Chinese New Year on 29/1/2006.