Sir Mark Thatcher has been subpoenaed to appear before a magistrate to answer questions related to his alleged financing of a failed coup in oil-rich Equatorial Guinea, a lawyer said Wednesday. The subpoena follows a request by the African country's government to question Thatcher, the son of former British Prime Minister Margaret Thatcher. "We received a subpoena late last night which requires Mr. Thatcher to appear before a magistrate on September 22," Mark Thatcher's lawyer, Alan Bruce-Brand, told The Associated Press.