The Wave demonstration took place in London on Saturday to mark the start of the Copenhagen summit this week. Somewhere in the region of 40,000 demonstrators converged to make their collective voices heard.

The event was sponsored by several organisations, with the Coop providing subsidised travel from all corners of the UK. Our group travelled on a train that left West Yorkshire in the wee hours of the morning. The general feeling was flat, perhaps a hushed anticipation, as the train pulled away, but a buzz started up around the train as the journey progressed. Pots of blue paint appeared to adorn the faithful as the wave began to ramp up.

Coaches were provided to get demonstrators across London to the starting point on Grosvenor Square. We walked across town, and were asked what footy team we supported. The blue face paint I guess. The general feeling was a lack of awareness of the demonstration. Was it going to be a flop?

At the meeting point, people were sloshing around the place, numbers building all the time, until a PA kicked into life and a line up of speakers and rousing music sent us on our way. There was a slight jostling as the crowd funnelled out the square, and then we were off through town to the Houses of Parliament, building momentum as we went.

It was great seeing the faces of shoppers as the surge of blue demonstrators rolled along. The rather forlorn and embarrassed looking counter demonstration at Nelson's column was barely noticeable (a handful of climate change sceptics with placards).

We mixed around the diverse crowd. Some walked in dignified protest, others danced along to soundsystems and Samba bands, others were leading chants and making a racket. Voices raised as the Houses of Parliament drew into sight, and whistles, hooting, and chanting reached a crescendo as we passed.

There were chants of '1, 2, 3, 4, we don't want coal anymore, 5, 6, 7, 8, CO2 is what we hate', 'What do we want? Climate Justice, When do we want it? Now!' and 'Gordon Brown, Don't let us down!'. The wave crashed down Whitehall, swirled around Westminster Bridge, and rolled back along the Southbank.

The good natured crowd went off on their merry ways, and that was that. It made a point: 40,000 protesters for climate justice and about 20 climate change sceptics. The public have got the picture, but have the politicians?