Fifty one years ago on this day, August 28, 1963, Martin Luther King Jr delivered a speech that continues to inspire. The US civil rights activist's philosophy of non-violent struggle drove millions of African-Americans to fight racial discrimination in the 1950s and '60s. In the wake of the shooting of a black teenager by a white policeman in the town of Ferguson this month and the ensuing unrest, it seems that King's dream has been deferred.

This isn't to suggest that King's campaign didn't produce results. Within a year if the speech, the Civil Rights Act was brought into effect, prohibiting discrimination on the basis of race, colour, religion, sex or national origin.

This clip shows King's speech from the steps of the Lincoln Memorial in Washington during one of the largest political demonstrations in US history.