Even Downton Abbey had a suggested romantic relationship between a young white female aristocrat and a Black male, in the early 1920s.
Until the 1950s, the Black population of London was never more than 1%-3%.
In fact, from 1850 to 1950, the Black population in London probably went down to 1%, because of the end of the African slave trade, plus stricter immigration laws.
Nearly all scientists are black in movies now also. And usually the only happy couples presented are gay.