This 21 January 2019 video from the USA says about itself:
In a Democracy Now! and Pacifica Radio Archives exclusive, we air a newly discovered recording of Dr. Martin Luther King Jr. On December 7, 1964, days before he received the Nobel Peace Prize in Oslo, King gave a major address in London on segregation, the fight for civil rights and his support for Nelson Mandela and the anti-apartheid struggle in South Africa. The speech was recorded by Saul Bernstein, who was working as the European correspondent for Pacifica Radio. Bernstein’s recording was recently discovered by Brian DeShazor, director of the Pacifica Radio Archives.
Martin Luther King Jr. and the fight for social equality: here.