This is a video of the London May Day demonstration in 2008.
From British daily The Morning Star:
THE co-ordinating committee of communist parties in Britain has called for a massive turnout on the London May Day march on May 1.
All socialists must support workers’ demands on the financial crisis and express solidarity with private and public-sector workers in their struggle in defence of jobs and conditions of service, it said.
The gathering at the weekend brought together representatives from the Communist Party of Britain, Communist Party of Greece, Tudeh Party of Iran, Communist Party of Sudan, Iraqi Communist Party, Communist Party of India (Marxist) and the Progressive Working Peoples Party of Cyprus (AKEL).
“The Londoner’s Guide to London” site lists various May Day events; but not one of those is political, trade union, etc.