Season 1 of Opportunity Knocks premiered on June 13, 1956.

Associated Rediffusion

Hosted by Hughie Green until 1978

Season 2 of Opportunity Knocks premiered on July 4, 1964.

ATV London

Season 3 of Opportunity Knocks premiered on July 3, 1965.

Season 4 of Opportunity Knocks premiered on July 2, 1966.

Season 5 of Opportunity Knocks premiered on April 29, 1967.

Season 6 of Opportunity Knocks premiered on March 16, 1968.

Season 7 of Opportunity Knocks premiered on August 21, 1968.

Thames Television

Season 8 of Opportunity Knocks premiered on December 25, 1968.

Season 9 of Opportunity Knocks premiered on September 8, 1969.

Season 10 of Opportunity Knocks premiered on June 15, 1970.

Season 11 of Opportunity Knocks premiered on March 15, 1971.

Season 12 of Opportunity Knocks premiered on November 8, 1971.

Season 13 of Opportunity Knocks premiered on August 7, 1972.

Season 14 of Opportunity Knocks premiered on August 6, 1973.

Season 15 of Opportunity Knocks premiered on August 5, 1974.

Season 16 of Opportunity Knocks premiered on September 29, 1975.

Season 17 of Opportunity Knocks premiered on October 4, 1976.

Season 18 of Opportunity Knocks premiered on September 19, 1977.

Season 19 of Opportunity Knocks premiered on March 21, 1987.

BBC - 21 March 1987 - 20 June 1987

Hosted by Bob Monkhouse

Season 20 of Opportunity Knocks premiered on March 5, 1988.

5 March 1988 - 4 June 1988

Season 21 of Opportunity Knocks premiered on March 4, 1989.

4 March 1989 - 3 June 1989

Season 22 of Opportunity Knocks premiered on March 31, 1990.

Hosted by Les Dawson