As a Cold War spycatcher, Smith exposed and arrested Soviet agents intent on stealing British nuclear secrets during the 1950s and 1960s. In 1961 he assisted in the arrest of George Blake, a double agent in British intelligence who fed the KGB details about secret British operations behind the Iron Curtain, the obituary said.

Smith was also instrumental in capturing the naval attachй John Vassall, who supplied Soviet agents with thousands of classified documents. He also helped break up the Portland spy ring, which was selling British nuclear submarine secrets to the Soviet Union. And he once hid in a cupboard to eavesdrop on Klaus Fuchs, a German-born physicist who provided Moscow with details about British and US atomic weapons, The Telegraph said.

When he wasn’t catching spies, Smith was sometimes assigned as a bodyguard to the former King Edward VIII, after the monarch abdicated to marry American divorcee Wallis Simpson. During one trip to London, the obituary said, Smith declined a gratuity offered by the duke with the terse: “I don’t take tips.”

In 1966, Smith was appointed to lead Britain’s Special Branch. After retiring in 1972, he devoted his time to reading poetry and enjoying a quiet life in the countryside, The Telegraph reported. Smith died on September 15.