Hundreds of people gathered on Saturday to demand the release of the last British resident in Guantanamo Bay.
Campaigners and human rights groups wanting a timetable for the release of Shaker Aamer, a father-of-four from Battersea, attended a rally, which was followed by a public meeting at Battersea Arts Centre.
Mr Aamer has been held inside the Cuban prison, run by the US, since February 2002, despite never being charged with any offence.
Both the UK and US have blamed each other for delays in his case.
Campaigners started the rally in Ponton Road - the new site for the US embassy which is less than a mile from where Mr Aamer’s wife and children, the youngest of whom has never met his dad, live.
The Save Shaker Aamer Campaign (SSAC), which organised the day, said people across the political and religious spectrum had united over the issue.
She said about 150 people attended the rally and a about 400 attended the meeting.
demonstrators heard speeches from Mr Aamer's lawyer, former Guantanamo detainee Moazzam Begg, a local Imam and from Martin Linton - former Battersea MP - and current Battersea MP Jane Ellison.
A spokeswoman for the SSAC said: “What was pleasing was to have so much diverse support in the local area.
“Particularly to have Muslim families with us, united over the same issue. We all want to bring Shaker home.”
Deputy Prime Minister Nick Clegg and Foreign Secretary William Hague, raised Mr Aamer’s case with the US Secretary of State Hilary Clinton recently.
And Kate Allen, director of Amnesty International UK, said more than 5,500 of its members in the UK had already contacted their MPs to raise concerns about Mr Aamer's plight.
Miss Allen told the Wandsworth Guardian last week her American counterpart was also due to meet Mrs Clinton to discuss the case, and that she was hopeful Mr Aamer's case was now moving up the political agenda.
She said: “When you have the Foreign Secretary (and the deputy Prime Minister raising these issues with the secretary of state and using meeting time on Shaker then I think you have more than the usual suspects campaigning here.”
To get involved in the Amnesty petition visit amnesty.org.uk/shaker