Teresa Hayter has been active in the Campaign to Close Campsfield since the immigration prison was opened, near Oxford, in 1993. She is one of the authors of the No One Is Illegal-manifesto. Before that, she was active in anti-racist and other campaigns.

Teresa Hayter has written seven books, including Aid as Imperialism (Penguin, 1971), The Creation of World Poverty (Pluto, 1981) and Open Borders: The Case Against Immigration Controls (Pluto, 2000, 2nd edition 2004). She is a graduate of Oxford University.