There weren't many black men playing professional football in the UK in the 1960s. Society as a whole was more racist (due, no doubt, to ignorance and the 'novelty value' of black people in public life).
Albert Johanneson's achievement was remarkable- to come from segregated South Africa and to rise to the top level in English football.
From 1960-1970 he made 200 appearances for Leeds United, scoring 67 goals. He then spent 2 seasons at York City.