Revelations about sex in Britain a few years after the war, including the disclosure that one in five women had an extra-marital affair, have been discovered in a university archive. Long before Britain could be thought to encourage a permissive society, one in five men confessed to a homosexual experience and one in four said he had sex with prostitutes.

Most women complained that their husbands were terrible in bed. These were the findings of the 1949 Mass Observation Project, Britain's first sex survey, which asked thousands of men and women nationwide at random about their sexual tastes, on condition of anonymity.

Mass Observation worked closely with the fledgling Marriage Guidance Council, formed in 1947, but the results were considered so outrageous that they were not made public, and the survey was buried in an archive at Sussex University.

A BBC4 documentary, Little Kinsey, to be shown on Oct 5, reveals the findings. The programme is so named because the survey was conducted a year after the Kinsey Report in America.