Wombles: The acronym stands for White Overall Movement Building Liberation through Effective Struggle.

This is a direct action anarchist movement based on Ya Basta! - the non-violent protest group which originated in Italy.

There is no leadership and tactics are agreed at meetings.

The Wombles plan to converge on London's Mayfair, the traditional venue for May Day celebrations.

It is encouraging people to use their "initiative" to create a street party, performance or pavement picnic.

Members will also hold a rally outside London's Horseferry Road magistrates court in support of the "Womble Seven".

They are on trial for alleged public disorder charges, after being arrested in central London, last October.

Critical Mass: A cycle group which campaigns for better public transport and an end to car culture.

They cycle around the city of London on the last Friday of every month and also organise protest rides in other cities.

For May Day they set off from Camden Tube Station and Camberwell Green and cycled to Trafalgar Square for a mass rally, stopping en route outside Horseferry Road magistrates court in support of the Womble Seven.

Trades Union Congress: The TUC has 70 member unions representing nearly seven million working people in the UK.

Its mantra is to "campaign for a fair deal at work and for social justice at home and abroad".

It is calling for a "peaceful celebration" of International Workers' Day.

An estimated 10,000 trade unionists will march through Central London from Clerkenwell Green to Trafalgar Square.

There a rally will hear speakers including Labour MPs, senior political figures such as Tony Benn and senior trade unionists from Britain and abroad.

London Animal Action: An animal liberation group which campaigns against the fur trade, vivisection and bloodsports.

It is launching "May Day Mayhem against the Fur Trade" in Ilford and outside Phillip Hockley Furs off London's Regent Street.

Sexual Freedom Coalition:Promotes reform of Britain's sex laws.

It is organising a parade by sex workers in Soho on Wednesday evening.