It was not hard to entice Dr Henry Kissinger to meet for lunch. Though he is 95, and moves very slowly, the grand consigliere of American diplomacy is keen to talk. He hops on and off planes to see the likes of Russian President Vladimir Putin and Chinese President Xi Jinping with as much zeal as when he played the global chess game as Mr Richard Nixon's diplomatic maestro. Persuading him to say what he actually thinks is another matter. Dr Kissinger is to geopolitical clarity what Mr Alan Greenspan was to monetary communication - an oracle whose insight is matched only by his indecipherability. It is my mission to push him out of his comfort zone. I want to know what he really thinks of Mr Donald Trump.

The timing is perfect. We are having lunch the day after Mr Trump met Mr Putin in Helsinki - a summit that America's foreign-policy establishment believes will go down as a low point in US diplomacy. Mr Trump had done the unthinkable by endorsing Mr Putin's protestations of innocence of electoral sabotage over the word of America's intelligence agencies. Geopolitics weighs heavily on Dr Kissinger. As the co-architect of the Cold War rapprochement with China and detente with the Soviet Union, Dr Kissinger now surveys a world in which China and Russia are both challenging the US world order, often in concert with each other.