London Greenpeace is described on a number of websites as:

" an Anarchist environmentalist activist collective that existed between 1972 and 2001.

In 1972 a group of activists around Peace News formed a new group committed to environmentalism and Anarchism. Initially called "Against the French Tests", they changed their name to Greenpeace - Stop the French Tests, campaigning against the testing of French nuclear weapons in the Pacific.

London Greenpeace was not affiliated with Greenpeace. Greenpeace was formed out of a rough coalition of various environmentalist groups in 1971, many of whom were already using the name "Greenpeace". London Greenpeace emphatically wanted to remain independent of this new and larger Greenpeace, which they saw as being too "centralized and mainstream for their tastes."

sources
London Greenpeace - History and Past Campaigns

No Logo - Naomi Klein

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In 1972, The Don't Make a Wave committee changed their official name to Greenpeace Foundation. While the organization was founded under a different name in 1970 and was officially named Greenpeace in 1972, the organization itself dates its birth to the first protest of 1971.[36] Greenpeace also states that "there was no single founder, and the name, idea, spirit, tactics, and internationalism of the organization all can be said to have separate lineages".

sources:

Michael Brown & John May: The Greenpeace Story

Greenpeace Official page: The Founders. Greenpeace.org.