I hated to have to do this, but I had to change your question, as it had multiple questions concerning different British colonies in Africa.  The editors are supposed to edit the question, if it involves multiple topics.  The best strategy would be to post them separately.  Since I already answered Kenya and Uganda, then you should only have Sierra Leone and South Africa left.

The Gold Coast Colony was founded in July 1874 by Great Britain.  The colony covered all the coastal land that is now in the country of Ghana.  Europeans called Ghana "the land of gold," because of its rich trading routes  The Gold Coast colony was also a strategically placed trading post.  The fertile land was also great for agriculture, and in 1878, the cacao tree was introduced from South America.  By the end of the 1800s, the colony was exporting half of the world's supply of cocoa. 

Great Britain withdrew from the Gold Coast Colony, because of the widespread nationalist movement started by educated African businessmen.  Representative from the country appealed for a constitution that included free elections.  In 1957, Ghana became the first country in Africa to be independent.