In OTL Paul Robeson was an incredibly impressive figure. However he gave uncritical support to Stalin's Russia. This deeply reduced his influence. I wonder if his position also made it easier for J E Hoover to push the lie that the Civil Rights movement was in some ways a Communist front.
Possibility,assuming he's got his son out of Russia at the time he visits the East End, or perhaps a part of Liverpool, Bristol or Cardiff with a black community that has been hit by an air raid and hears ridiculous comments by the CP about WW2 simply being an imperialist struggle.