László Péter was Emeritus Professor of Hungarian History at the University of London. He completed his first degree at the Eötvös Loránd University of Budapest after which he worked as an archivist and teacher. He left Hungary in 1956, subsequently completing a DPhil in Oxford under the supervision of C.A. Macartney and John Plamenatz. In 1961, he was appointed to a lectureship at SSEES and to a full chair in 1990. He retired in 1994.
László Péter published extensively on the constitutional history of Hungary and the Habsburg Monarchy, mostly in the nineteenth century. He was an External Member of the Hungarian Academy of Sciences and a Fellow of University College London.
During the Hungarian Revolution of 1956, Péter was appointed to the revolutionary committee charged with the supervision and cataloguing of the archives of the Ministry of the Interior.