Never able to qualify out of the Interzonal stages into the Candidates' series, Miles eventually lost the race to become the first British Candidate when Short did so in 1985. However, he retained top board for England at the Thessaloniki and Dubai Olympiads of 1984 and 1986, helping the team to silver medals at each.
Miles also clashed with chess authorities and with his fellow English players, particularly Keene and Short. Miles made accusations regarding payments that Keene had received from the British Chess Federation for acting as his assistant in the 1985 Interzonal tournament in Tunis. Miles became obsessed with the affair, eventually suffering a mental breakdown over it. He was arrested in September 1987 in Downing Street, apparently under the belief that he had to speak to then-Prime Minister Margaret Thatcher about the matter; he was subsequently hospitalised for two months. Writing in The Daily Telegraph in November 2003, Nigel Short said that "Tony was insanely jealous of my success, and his inability to accept that he was no longer the UK's number one was an indication of, if not a trigger for, his descent into madness."