Seen in retrospect, the Reagan–Thatcher relationship does not seem a difficult one. They had natural affinities, and easily developed a warm friendship. But at the time it was not so simple. In many ways it was like Churchill’s encounters with Roosevelt – friendly, even affectionate at times, but masking important differences of interest between the two countries that threatened to come to the surface and had to be covered by skilful diplomacy. As Palmerston used to say, there was no such thing as permanent friendship between countries, merely permanent interests that vary from time to time.