Stephen Tuck is a history lecturer at Pembroke College, Oxford, a visiting fellow at the W.E.B. Du Bois Institute at Harvard and the author of We Ain't What We Ought to Be: The Black Freedom Struggle From Emancipation to Obama.

...In Britain and on the American right, there were suspicions that ethnicity played into Obama's apparent snub -- the son of a Kenyan would understandably not be enamored by the daily reminder of a prime minister whose second term had overseen the suppression of the Mau Mau rebellion. But in their op-ed, Obama and Cameron pointedly began by quoting Churchill and celebrated the fact that the two nations "support the human rights and dignity of all people."...

Nonwhite citizens in both countries have suffered discrimination. Activists in both countries have sought to force Britain and America to live up to their creeds of human rights and dignity for all people, regardless of color. And during the era of the civil rights movement in particular, the connections between activists across the Atlantic were strong, and influential. 

This rather more grassroots version of the special relationship -- like the official version -- started in World War II. More than 100,000 American black American soldiers were stationed in Britain, swelling Britain's black population tenfold in the process.

The GIs arrived in segregated army units. Off-duty fights with their white American counterparts were common. But the British War Cabinet would not allow segregation off-base, and the British public mostly sided with the black GIs. The experience of equality abroad inspired many African-American veterans to fight Jim Crow upon their return....