Learning about your heritage is nice. My grandfather was a double spy during WWII for between the Germans and the Dutch. Many stories have been lost with his departure and for good reason. Most people do not need to know of his experiences. He was one of the best people you would ever get to know.
I did try a quick search, not sure if any of this is him, but the dates would seem to correspond.
Samuel Cromwell - Wikipedia, the free encyclopedia
ExecutedToday.com 1842: Philip Spencer, Samuel Cromwell and Elisha Small, on the ship yardarm
http://militaryhistory.suite101.com/...rs_mutiny_1842