During the Friday rally outside Downing Street, the demonstrators raised their voices in solidarity with others around the world to shine a spotlight on the fate of the man they say is a pioneer for justice and a peaceful activist, press tv reported.
"It is completely horrendous to behead someone simply because of their freedom to express their views about a particular political ideology or regime," a protester said.
Frank Gelli, an Anglican priest, also said, "All Sheikh Nimr wants is justice, a freedom for his people and reform, like any decent human being and indeed someone who is motivated by faith would actually demand, so what is happening is intolerable."
The demonstrators also urged British Prime Minister David Cameron to intervene in the case of the Shiite cleric.
"Hopefully David Cameron can actually find out what his people want in the UK, go to the Saudi Embassy and actually say ‘you know what, this is wrong, what’s happening, and you lot need to stop this," another protester said.
The demonstrators promised to continue their call to action until Sheikh Nimr is released.
On October 15, Nimr’s death sentence was upheld by the Specialized Criminal Court in the Saudi capital, Riyadh. In reaction to the sentence, people took to the streets in the city of Qatif in Saudi Arabia’s Eastern Province to condemn the move. There have also been demonstrations in other countries.
The senior Saudi Shiite cleric, who was attacked and arrested in July 2012, is accused of delivering anti-regime speeches and defending political prisoners.
Human rights activists say the sentence issued for Sheikh Nimr was politically motivated.
Amnesty International has called the death sentence "appalling", saying the verdict should be quashed.
