Anti-war protesters from around the North West joined thousands more from across the country to hold the first major demonstration since the fall of Saddam Hussein.
The organisers of the event called for British troops to be pulled out of Iraq.
The day of protest was organised by the Stop the War Coalition, the Campaign for Nuclear Disarmament (CND) and the Muslim Association of Britain.
Kate Hudson, chairman of CND, said, "This has been organised to send a very strong message to the Government that the British population doesn't approve of us taking part in a war based on lies, which has led to the illegal occupation of a country, or any other pre-emptive war on trumped up charges."
Abid Mirza, 32, of Accrington travelled to the march with friends. He said, "We have been led into this war by the American government and are now being used to restore order in the country. If the UK and America want to proclaim the values of freedom then I think they should practice what they preach. "
"It was good to see so many people from all walks of life attend the march."
As the protesters marched along Hyde Park, en route to the rally in Trafalgar Square, many carried banners with slogans like 'Blair must go' and 'UK troops out of Iraq'.
Veteran Labour politician Tony Benn was greeted with loud cheers when he walked onto the stage at Trafalgar Square.
He told the crowd, "America went in and stole the oil and is now trying to sell all the other Iraqi companies and properties."
The event was criticised by some groups, with the Iraqi Prospect Organisation (IPO) launching its Democracy for Iraq campaign in opposition to the march.
Ahmed Shames, chairman of the IPO, said, "What Iraq and Iraqis need are productive measures that will help them achieve democracy and sovereignty."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article