He was formally taken on by the Foreign Office in 1960, working on its intelligence assessment staff. There he developed an encyclopedic knowledge of the disposition of Warsaw Pact forces, carrying the career details of many figures from the Soviet command in his head.
The value of this expertise was quickly recognised, and Mackintosh was permitted to share his knowledge with allies including America, where audiences for his briefings including Senators Henry “Scoop” Jackson and Ted Stevens. Later George Bush Snr (a CIA Director before he became President), invited Mackintosh to the Oval Office.
Back in Britain, Mackintosh was asked by Sir Anthony Duff, chair of the Joint Intelligence Committee, to remain in an advisory role with the Cabinet Office beyond normal retirement age. In the mid-1980s he played a pivotal role in the critical debate which ended with Margaret Thatcher being persuaded that the West could “do business with” the new Soviet leader, Mikhail Gorbachev .
Mackintosh emphasised that the weight of history in a nation that had lost 27 million people in the Second World War (and therefore considered a nuclear war to be survivable) meant that it was unrealistic to think that the Soviet system and the attitudes that had sustained it could change overnight, if ever. Initial “reforms” to the Soviet military had been designed to respond to Western technological superiority and did not represent any kind of new thinking. If Gorbachev was sincere about his desire to transform the Soviet military system, Mackintosh warned, it would be a long struggle and he would be up against hugely powerful entrenched interests.
But, he believed, there was good reason for believing that Gorbachev could be persuaded to negotiate in good faith: the Soviet economy was creaking towards bankruptcy and he had little choice. As Mackintosh saw it, Gorbachev was the first Soviet leader to realise that, to preserve the USSR, he had to do something to boost the non-military aspects of the economy. It was arguments like these, backed up by hard evidence, that enabled Mrs Thatcher to convince a sceptical Reagan administration that there was a real prospect of progress, and which led to a series of face-to-face meetings between the American and Soviet leaders and genuine negotiations on Strategic Arms Limitation and human rights. ...