On television, he presented Panorama and chaired Question Time, and on radio was presenter of The World at One.
Day was born in Gloucester, and was educated at St Edmund Hall, Oxford. While a student, he was elected president of the Oxford Union debating society. He was called to the Bar in 1952, but spent his entire career in journalism.
Day first rose to prominence on the then upstart Independent Television Netork (ITN) in the 1950s, when he was the first British journalist to obtain an interview with President Nasser of Egypt after Britain's humiliating defeat in the Suez Crisis.
In the 1959 General Election he stood as a Liberal Party candidate for Hereford but failed to win the seat.
He became known in British broadcasting circles as "the Grand Inquisitor" for his abrasive style of interviewing politicians, a style that was radically out of keeping with the British media's culture of deference to authority and office that prevailed during the early days of his career. In 1981, he was made a Knight of the Order of the British Empire for his services to broadcasting.
In October of 1982, during an infamous interview with the then Conservative Secretary of State for Defence John Nott, whilst pursuing a line of questioning regarding cuts in defence expenditure, he posed the question "But why should the public, on this issue, as regards the future of the Royal Navy, believe you, a transient, here-today and, if I may say so, gone-tomorrow politician, [a reference to Nott's announcement that he was to stand down at the next General Election ] rather than a senior officer of many years?" John Nott promptly rose from his seat, removed his microphone, said "I'm sorry, I'm fed up with this interview. Really, it's ridiculous." and walked off the set. John Nott's autobiography published in 2003 is called Here Today Gone Tomorrow: Recollections of an Errant Politician.
Robin Day published two autobiographies; Day by Day in 1975 and The Grand Inquisitor in 1989.