Kapur Singh was born in a Lyallpur canal colony chak in 1909, took a first at Government College Lahore and read moral sciences at Cambridge, and entered the Indian Civil Service.
He was suspended from the service in 1949 and dismissed in 1953 over charges he always maintained were fabricated. He then wrote and entered politics, serving as a member of both the Lok Sabha and the Punjab Assembly.
He is known for two things. The first is his writing, in English and Punjabi, on Sikh philosophy and history, of which Parasaraprasna is the principal work, written in a dense and highly learned register unlike anything else in the field.
The second is his claim, made repeatedly, that a circular was issued in 1947 by the Government of India describing Sikhs as a criminal tribe. The document has never been produced. The claim has been influential in Sikh political argument and remains unverified.
The Anandpur Sahib Resolution's drafting is associated with him. The Akal Takht gave him the title National Professor of Sikhism.
He was an Indian Civil Service officer dismissed in 1949 in a case he always maintained was political, and he spent the rest of his life as a scholar and a politician.
Sachi Sakhi is his account of that period and of the Sikh political position after 1947, and it is one of the most cited and most argued about books in modern Punjabi.
He wrote in Punjabi and English on Sikh philosophy, was a member of parliament, and drafted the Anandpur Sahib Resolution's intellectual case. He died in 1986.