Each breakdown or setback during the early years of Smith's premiership prompted press speculation that Harper might replace him. In 1966, when Smith brought a working document back from the HMS "Tiger" talks with the British Prime Minister Harold Wilson, Harper led opposition to the terms in Cabinet, contributing to their rejection. Harper resigned from the Rhodesian Front in 1968, soon after Smith dismissed him from the Cabinet, reportedly because Harper had had an extramarital affair with a British agent. He subsequently became a vocal critic of the Prime Minister, greeting each step Smith made towards settlement with black nationalists during the Bush War with public indignation. By the time black majority rule began in Zimbabwe Rhodesia in 1979, following the Internal Settlement of the previous year, Harper had left for South Africa, being unwilling to accept majority rule in Rhodesia. He died in 2006 at the age of 90.