The non-British colony which is a member of the Common wealth is

Explanation

Mozambique was never a British colony; it was a Portuguese colony. However, it joined the Commonwealth of Nations in 1995, becoming the first country with no historical ties to Britain to do so. Other non-British colonies that later joined the Commonwealth include Rwanda, which became a member in 2009. However, since this question was set in 2003, Mozambique is the best answer to this question.