A two-day strike by council workers over pay is taking place across England, Wales and Northern Ireland, the biggest public sector action for years.
The walkout by hundreds of thousands of workers has forced schools to close and affected services such as refuse collection.
Employers say 300,000 Unison and Unite members have joined the action but the unions say the figure is 500,000.
Workers have rejected the 2.45% pay offer from local authorities and are calling for 6%.
They say because the cost of living has risen, the offer actually constitutes a pay cut.
General secretary of Unison Dave Prentis threw a giant cardboard 20p piece into the River Thames as part of the protest. He said his members were struggling to pay for staples like milk and bread.