In 1966, though, coalition politics reached its bizarre apotheosis in the so-called Grand Coalition, when the junior partner of the CDU/CSU became not the FDP but the SPD, their principal antagonist, hitherto apparently doomed to serve as the permanent Opposition. Willy Brandt was bounced into the arrangement against his wishes by his colleagues Herbert Wehner and Helmut Schmidt, because the plane bringing him from Berlin to the crucial meeting was delayed by fog. But, once again, the arrangement worked. Brandt himself, with his charm, his fluency in other languages, and his impeccable political past, made a natural Foreign Minister. And although he loathed Georg Kiesinger, the CDU Chancellor and a former member of the Nazi Party, to the point where he claimed to feel physically ill in his presence, the coalition lasted for three years, and is regarded by some commentators as one of the most successful governments in the history of the Federal Republic.

The elections in the autumn of 1969 transformed the politics of coalition once again. Although it still trailed the Christian Democrats, the SPD picked up enough seats to raise the possibility of securing a slim majority in the Bundestag by going into coalition with the FDP. Wehner and Schmidt were against it; they wanted to continue with the existing arrangement. With entirely uncharacteristic decisiveness, Brandt seized his chance. Wehner and Schmidt had bounced him into the Grand Coalition; now he bounced them out of it. Without a word to either of them he went on television on election night and announced that he would seek to form a new government with the FDP. He succeeded, and three weeks later the new Bundestag elected him Chancellor.

Which is where my play begins.

Two mutually contradictory developments had conspired to bring the SPD and the electorate somewhat closer together. The first was the change in the nature of the party that had begun at its conference in Bad Godesberg ten years earlier, when Brandt, Wehner and Schmidt had persuaded it to dump its residual Marxism in favour of the so-called social market economy. The second was the change in the nature of the electorate brought about by the events on the streets of Germany in the previous year.