American civil rights campaigner the Rev Jesse Jackson says the UK's "big challenge" is to "choose inclusion".
Britain had to build a "new nation" a nd in a speech to Cambridge University students, he said people had to learn to live together and grow.
"Too many Americans do not realise-and perhaps too many Europeans as well do not yet realise-that most people in the world are black, brown, yellow, young, female, non-Christian, and don't speak English," he told the Cambridge Union Society.
"And the formerly colonised peoples are now moving away from the monochrome, all 'one-ethnic- group' societies.
"This is Europe's big challenge for the future, and the UK's big challenge, to build a new nation, to choose inclusion.
"We must unlearn earlier lessons we learned too well. We learned how to survive apart.
"We must now learn a new lesson-how to live and prosper together, choosing inclusion which leads to growth."
He told the student debating society: " A comprehensive policy of democracy and inclusion is the road map to a new England, to serve the emerging, diverse world."