company controlled by Wafic Saïd, a middleman in the deal. In 1986 his mother again faced questions in the House of Commons, this time over her son's relationship with the Sultan of Brunei. Sir Bernard Ingham, the Prime Minister's press secretary, suggested that he could best help the government win the 1987 general election by leaving the country. Margaret Thatcher's biographer, David Cannadine, stated that Mark Thatcher "traded shamelessly on his mother's name" and that he "continued to attract controversy and investigation from the tax authorities", much to his mother's embarrassment. Alan Clark mentions the "Mark problem" in his published diaries. He moved to Texas, where he worked for David Wickins of Lotus Cars and British Car Auctions and met his first wife in 1987. In the United States he started Monteagle Marketing, a profitable company that sold whisky and clothing. During this period he spent some time in Switzerland as a tax exile, until he was forced to leave after the Swiss authorities began to question his residency qualifications. He helped arrange a contract for his mother's memoirs in the 1990s. A security alarm business he ran in the United States failed and in 1996 he was prosecuted for tax evasion, at which point he moved to Constantia, South Africa, with his wife and their two children. In 1998 South African authorities investigated a company owned by Thatcher for allegedly running loan shark operations. According to the Star of Johannesburg, the company had offered unofficial small loans to hundreds of police officers, military personnel and civil servants, and then pursued them with debt collectors. He claimed that officers had defrauded him and charges were dropped. It was also suggested that he had profited from contracts to supply aviation fuel in various African countries. In 2003, following the death of his father, he was allowed to use the title of 'Sir' due to his inheritance of the Thatcher baronetcy a year before he was arrested in South Africa in connection with the 2004 Equatorial Guinea coup d'état attempt. He pleaded guilty to breaking anti-mercenary legislation in January 2005. At this time the Sunday Times suggested that he had personal assets of £60 million, most of which was in offshore accounts. In 2016 historic documents relating to Thatcher and Oman, expected to be released under the 30-year rule, were retained by the Government. The Guardian noted that the decision was made