The Reverend Jesse Jackson addressed the Cambridge Union
A US civil rights campaigner believes Britain is ready for a political "breakthrough" with black people running for office "at every level".
The Reverend Jesse Jackson told Cambridge University students black Britons should be inspired by Barack Obama becoming president of the USA.
"There is something about freedom that is contagious," Mr Jackson said.
"Britain's ready for a breakthrough," said the campaigner who twice tried to become America's first black president.
Mr Jackson said he could not predict when Britain would elect a black prime minister.
He said: "You've already had a woman prime minister. What is there about 10 Downing Street that a black man or woman could not do?"
Mr Jackson told the Cambridge Union, the university's debating society: "As the black and ethnic minority population grows, so too will their voting and political power and their demand for equality and a level playing field.
"Taken together this vote, as it has in the US, can determine the margin of victory in the UK's upcoming elections.
"Britain's new leaders, the emerging leaders of your generation, are challenged to move away from living in isolation.
"They are asked to commit to forging a multi-cultural, multi-racial inclusive society - a one big-tent Britain and a one big-tent Europe."