What is Black Lives Matter?
BLM started in the US as a reaction to the fatal shootings of black people by white US police officers.
So what are the aims of the British branch?
The British arm is protesting against what it says is a disproportionate number of black people among those who die in police custoday in Britain.
The campaign, called #Shutdown, is also protesting about the targeting of minorities by law enforcement authorities and employment and social inequalities.
What happened at Heathrow Airport?
Activists lay across the slip road off the motorway at Heathrow. They cemented their arms into concrete tubes.
Police and ambulance crews had to saw and chisel the cement blocks away from protesters’ arms. There were severe traffic delays.
Ten people were arrested.
What about Nottingham?
In the central England city of Nottingham, BLM campaigners lay across the tramlines in the city centre.
Demonstrations were also staged in Birmingham and Manchester on Friday, the fifth anniversary of the death of Mark Duggan.
His shooting by police five years ago helped spark several days of rioting in the UK.
What they are saying
“This is a tactic which has been long employed. It goes back to the civil rights struggle. You can see civil disobedience being used as a tactic during attempts to end segregation in American society, but also we have seen it more recently in the US where they have shut down motorways, they have shut down shopping malls,” – activist Wail Qasim defends the disruption caused by the protest.