Brown suffered from dementia and died July 15, the Washington Post reported.
After serving as a photographer in the Royal Air Force, Brown became journalist. During his career on Fleet Street, he was known as a hard-drinking, free-spending and adventurous reporter who interviewed Egyptian President Gamel Abdel Nasser, took a ride on the first nuclear submarine and smuggled a Boris Pasternak poem out of the Soviet Union, claiming he lost a second poem during a drunken night in Berlin.
Brown eventually settled in Washington, saying he was drawn to the U.S. capital by the Freedom of Information Act. His first book, "Bodyguard of Lies," described Allied efforts to deceive the Germans about the D-Day invasion.
His other books included biographies of "Wild Bill" Donovan, the founder of OSS, and British spymaster Stewart Menzies. "Treason in the Blood" was about Kim Philby, the British double agent, who Brown had known in Lebanon.
His last book, "Oil, God and Gold," about the oil company Aramco, was published in 1999.