Martin Luther King with wife Coretta, who is said to have complained that if he spent 10 hours a month at home, ‘it would be an exaggeration’

He will always be remembered as one of the greatest orators in history, a winner of the Nobel peace prize whose “I have a dream” speech proved a defining moment of the American civil rights movement.

Yet the reputation and legacy of Martin Luther King Jr may be facing what one of his biographers has described as a “painful historical reckoning” after shocking new revelations about the Baptist clergyman’s relationships with women.

The couple pictured in Alabama in 1956, three years after they married MICHAEL OCHS ARCHIVES/GETTY

A huge archive of documents recently released from Federal Bureau of Investigation files exposes in detail King’s extramarital sexual activities with dozens of women as he travelled the country campaigning against racial inequality.

In one memo written after the FBI bugged King’s room at a Washington hotel, there is a startling foreshadowing of