Peter Sedgwick (1934–1983) was a translator of Victor Serge, author of a number of books including PsychoPolitics and a revolutionary socialist activist.
Peter Sedgwick grew up in Liverpool and won a scholarship to Balliol College, Oxford, where he became a member of the Communist Party of Great Britain. In 1956, after the Hungarian Revolution, he left and joined the Socialist Review Group, later the International Socialists (forerunners of the Socialist Workers Party). He wrote for the group’s press while also getting involved in the activities of rank-and-file members. He was opposed to the International Socialists' renaming themselves the Socialist Workers Party in January 1977 and refused to join the new organisation. However, he remained dedicated to the far left. Christopher Hitchens called him "a noble remnant of the libertarian left" and dedicated his book Letters to a Young Contrarian (2001) to Sedgwick's memory.
For the 15 years until his death Sedgwick earned his living as a lecturer in politics at the Universities of York and Leeds.
In his book PsychoPolitics (1982) he explained the severe reductions in psychiatric services that were already taking place as an effect of the "politically correct" conceptions of mental illness, such as those of the anti-psychiatry writers Michel Foucault, R.D. Laing and Thomas Szasz, being exploited by governments to justify spending cuts. Ben Watson (music writer) has compared the spirit of Sedgwick's work to the later campaigns of the Mad Pride movement.