Witness

How a young American scientist began the work that would show how our climate is changing. His name was Charles Keeling and he meticulously recorded levels of CO2 in the atmosphere. His wife Louise and son Ralph spoke to Louise Hidalgo about him in 2013. (Photo: Thick black smoke blowing out of an industrial chimney. Credit: John Giles/PA)

The US first began sending troops to the UK in 1942 to help in the war effort. It is estimated that at least two million American servicemen passed through the UK during World War Two and tens of thousands of them were black. The African-American GIs stationed in Britain were forced by the American military to abide by the racial segregation laws that applied in the deep south of the US. But that didn't stop relationships developing between British women and the black soldiers, some of whom went on to have children. Babs Gibson-Ward was one those children. She has been speaking to Farhana Haider about the stigma of growing up as mixed raced child in post-war Britain. (Photo: Hoinicote House children, c.1948. Boys and girls whose parents of mixed ancestry met during WWII. Credit: Lesley York)

In 1963 a small group of British black activists started a pioneering protest against racism within the local bus company in Bristol. It had specified that it did not want to employ black bus drivers. Inspired by the example of the US Civil Rights Movement the boycott ended in victory and led to the passage of Britain's first anti-discrimination laws. Paul Stephenson and Roy Hackett spoke to Louise Hidalgo in 2013 about their part in the protest. Photo: Park Street in Bristol in the early 1960s. (Credit: Fox Photos/Getty Images)

In August 1958 Britain was shocked by nearly a week of race riots in the west London district of Notting Hill. The clashes between West Indian immigrants and aggressive white youths known as Teddy Boys led to the first race relations campaigns and the creation of the famous Notting Hill Carnival. Using voices from the BBC archives Simon Watts tells the story. Photo: Street scene in Notting Hill at the time the race riots broke out in 1958. Credit: Getty Images.

In 1987 Diane Abbott became the first black woman elected to the British Parliament. The daughter of first generation immigrants she was one of only four black MPs elected that day. In 2015 Diane Abbott spoke to Farhana Haider about her journey into the political history books. Photo: Diane Abbott in 1986. Copyright: BBC