Public sector strikes
The strikers making up the biggest public sector walkout in a generation came to London with a smile.
The atmosphere on the march here on Whitehall was warm, friendly, even jovial. Protesters chatted amicably with the police, many of whom were sufficiently relaxed to fold their arms, or put their hands in their pockets.
The whole tone of the day, at least until mid afternoon, felt very different from the student demonstrations here before Christmas. More mature, more considered, more female. But no less determined.
Rachel, a teacher, told me she thought it was ridiculous that she'd be expected to teach a class of five year olds in her late sixties.
Another teacher replied "I hope so", with a defiant grin, when I asked him if he thought there would be more strikes like this.
The trade unions claim up to 20,000 took part in the demonstration, which snaked its way through the streets of London for three to four hours.
It was only when some marchers had gone home, and others were at a rally where trade union leaders were speaking, that the atmosphere changed.
A small group of young men - perhaps around 30 to 40 of them - dressed in black hooded tops, started to run around Parliament Square, and head for Whitehall.
I ran with them, and so did the police. Suddenly they didn't have their hands in their pockets. They were poised, and hurriedly being briefed. A row of police vans took up position at the top of Whitehall, near Trafalgar Square, and in front of the vans stood several lines of police officers.
But the mixture of bravado and excitement didn't amount to much. Within 20 minutes or so, many of the protesters had dispersed.
Many told me they expected to be back, and looked forward to being back: waving their banners, chanting their songs and sticking up for what they believe in.
Chris Mason is out political reporter, and has been covering the strikes in central London all day on 5 live. Follow him on Twitter.