"the negroes were hanging round the public house doors in tight natty suitings"

Zoot suit
Creative Commons AttributionZoot suit - Credit: sweet lil' bunny
The word negro was fairly commonplace in 1930s Britain, and was seen as a neutral term rather than a slur. However, racial prejudice was widespread at the time.

The 'tight natty suiting' is most likely to be a zoot suit, a style of dress that originated in Harlem jazz culture, tapered at the ankles whilst billowing at the cuffs.