[1] Born in Barbados, Braithwaite went to sea with the British merchant navy as a teenager and travelled the world as a sailor.
[2] After World War I he lived in New York City for a while, before moving to settle in London, working for the Shipping Federation.
In 1933 he followed George Padmore in resigning from the CPGB in protest at the implicit shift away from anti-imperialism involved with the emerging "Popular Front" strategy.
He became organising secretary of the International African Service Bureau (IASB), established in May 1937, whose members included Padmore, C. L. R. James, Jomo Kenyatta, Amy Ashwood Garvey and I. T. A. Wallace-Johnson.
Braithwaite wrote a monthly column, "Seamen's Notes", for the IASB journal, International African Opinion.