Rawle was born in Roseau, Dominica, where his Trinidadian parents, William Alexander Romilly Rawle and Elsie Elizabeth Sophia Garrett, had moved; his father was head of the local branch of the West India and Panama Telegraph Company, the precursor of Cable and Wireless.
Rawle was born in Roseau, Dominica, to his Trinidadian parents, William Alexander Romilly Rawle and Elsie Elizabeth Sophia Garrett. His father served as the head of the local branch of the West India and Panama Telegraph Company, an organization that later became Cable and Wireless.