He first came to Parliament Square as part of a six-day vigil to protest against the Iraq sanctions in January 2001. He returned on June 2 to continue to protest against Britain's decision to join the US in the Iraq war.
Dubbed Tony Blair's most persistent critic he said: "I had a little grey chair, a backpack. I was sleeping in a survival bag with a sleeping bag. I didn't even have an umbrella."
Since then he has mounted a one-man anti-war vigil outside Westminster.
In October 2002, he won a landmark case in the High Court, in which the judge ruled that Brian was exercising his right to freedom of speech in Parliament Square, his placards did not constitute advertising, and that any pavement obstruction was not "unreasonable".
In 2005 the Serious Organised Crime and Police Act (SOCPA) was drawn up, including provisions aimed at removing Haw from Parliament Square.
A High Court hearing ruled that Mr Haw's protest was not covered by the legislation because the law could not be applied retrospectively.
Haw was officially nominated as a candidate in the general election for the Cities of London and Westminster on 21 April 2005 although he failed to win the seat.
On December 11 05 one of America's most vocal anti-war protesters, Cindy Sheehan, who lost her son, a US soldier, in Iraq visited Haw. Mrs Sheehan set up a similar camp to Haw camp outside President Bush's ranch in 2005. Her son Casey, a Marine, was killed in action in Baghdad in April 2004.
On May 23 2006 78 police officers dismantled Haw's display of posters and placards in a night-time raid later branded "overkill". It is thought to have cost the tax payer around £7,000. Among the items that were removed was a signed artwork by Banksy, the graffiti artist.
Then Liberal Democrat MPs Susan Kramer and Vince Cable offered a new poster to Brian Haw on May 24 to help replace those taken by police. Ms Kramer said: "I have always been proud that we allow a protest in front of Parliament. It is a reminder that we live in a democracy. Brian's protest has been no threat to national security and the decision to reduce his display to insignificance is petty. If we don't oppose this, they will soon be removing Brian altogether. That would be a sad day for freedom of speech."
In January 2007 the artist Mark Wallinger installed a major work of art in Tate Britain. ‘State Britain’
consisted of a complete replica of Haw's display just before it was dismantled by police. He later won the Turner Prize for the work.
In February 2007, Brian was voted Channel 4: 'Most Inspiring Political Person of the Year'