This was followed in 1880 as private secretary to Sir G. C. Strahan, administering the Government of the Cape, and in 1881, removed to British Guiana as a Puisne Judge from 1882 to 1883.
While Governor-in-Chief at Sierra Leone, from 16 May 1892 to January 1894, he witnessed in November 1892 the first systematic strike of the 800 underpaid labouring men of the Royal Engineers' Department in the history of that colony.
The previous governor, John Joseph Crooks, disagreed with Fleming and referred to the raise in pay as a "capitulation."
Throughout 1893 there were a number of times in which native leaders from the Mende, Sherbro and Temne communities took their concerns directly to Fleming who proved willing to listen.
Their only son, Hugh Joseph (born 26 Jan 1895 in Warwick), became a second lieutenant and was killed in action during World War I on 24 August 1916 at Nord-Pas-de-Calais, France.