Anger with the Government has prompted recent publicity stunts.
Greenpeace may be non-political, but its anger at UK environmental policy, particularly the recent lurch towards nuclear energy, seeps from every pore. "It's hard to adequately communicate the sense of despair about what's happened between NGOs and the Government," says its campaigns director, Blake Lee-Harwood.
"Frankly, this lot are gutless. In eight years, this Government has been incapable of formulating a clear, well-balanced policy. It has been incompetent."
He sounds sad as well as angry, because he feels in some way complicit.
"Six months ago, we were rightly criticised for giving them too much slack and hanging on to what they told us in 1997, when they were first elected," he says. "In the past six months, we have turned as a movement."
That was unmistakeably evident only recently, when two Greenpeace protesters unfurled an anti-nuclear banner from the rafters before a Tony Blair speech to the Confederation of British Industry.
"We had heard that some very large vested interests were having a major influence on Blair, talking him into nuclear," he says. "We wanted to tell him that he might think he could come to a cosy club of business people and pull a fast one, but we would challenge him all the way and there would be political consequences."
He won't reveal operational details, but he says the stunt was spontaneous and easy to execute. "It was not difficult to get in," he adds.
Newspaper headlines from the day line the walls of Greenpeace's ecologically designed head office in Islington, north London. Greenpeace has never had a problem attracting publicity, but action is always the bottom line.
"The world faces many problems, but we are making small amounts of progress," says Lee-Harwood, who gives as examples its campaigns to prevent illegal logging in ancient rainforests and to stop genetically modified food.
However, he admits that the organisation is not making much headway on big issues such as renewable energy and climate change. "We've screwed the right rhetoric out of the political establishment, but we've been unable to get the right action," he says.
Expect an angrier Greenpeace, says Lee-Harwood. "We have to start throwing our toys out of the pram," he says. "We need to build alliances and bring in other groups that are prepared to get as serious as us. Either we do something or we all die."
Greenpeace is one of the primary players in Stop Climate Chaos, the charity coalition formed to mobilise public concern about climate change. It will be interesting to see whether the coalition will speak with the bluntness of Lee-Harwood, who works for an NGO that refuses to accept money from business or government and is prepared to break the law.
"We feel happier not to be bloated with corporate cash," he says, adding that this is not intended as a slight on WWF-UK, another coalition member that has 18 corporate partners.
He says other organisations "could do better" on campaigning, and welcomes the NCVO's bid for lottery funding to establish a campaigning hub. But he doesn't think everyone should ape Greenpeace methods. "The likes of WWF do a great job in engaging at a different level," he says.
As a lifelong activist, which voluntary organisation does he most admire?
"Oxfam is head and shoulders above anybody else in the development sector," he says.
Being campaigns director of Greenpeace in swanky Islington sounds like every student's dream. Although Lee-Harwood insists he won't stay forever, it's hard to see him ending up working in a bank.