I've found lots of people in all four home countries of England, Wales, Scotland and Ireland; then I've found BMDs or substantial involvement in the following, using their names at the time: Antigua, Argentina, Australia, Austria, Bermuda, Borneo, Brazil, Burma, Canada, Ceylon, Chile, China, Colombia, Corfu, Cuba, Denmark, Dominica, Estonia, France, Germany, Gibraltar, Greece, Guernsey, Guyana, Hong Kong, India, Italy, Jamaica, Japan, Jersey, Kenya, Korea, Latvia, Liberia, Malta, Mexico, Norway, Nyasaland, Persia, Peru, the Philippines, Poland, Portugal, Russia, Sierra Leone, Singapore, Somaliland, South Africa, Southern Rhodesia, Spain, St Helena, St Kitts, St Vincent, Sudan, Sweden, Switzerland, Texas (while it had its brief independence), Thailand, the Canaries, Turkey, United States and Zanzibar. It's been an amazing introduction to history and geography.
Updated in December 2012: add Morocco to the list!