A s Wordsworth found in Paris after 1789, revolutions are deeply enthralling. There is nothing so bold, so self-sacrificing, so brave, so cruel as a revolutionary crowd. What’s more, revolutions have shaped the modern world. The European Union has been transformed by the overthrow of Marxism-Leninism in eastern Europe, while the near-revolution in Tiananmen Square in 1989 feeds the neuroses of the Chinese Communist party to this day. Yet in some ways it was a revolution 10 years earlier that has been even more formative for our times: the overthrow of the shah in Iran . That, indeed, was a genuine revolutionary archetype on the 1789 model: barricades in the streets, crowds armed with old hunting rifles and kitchen knives facing up to the tanks (British-made, naturally); palaces, barracks and secret police headquarters stormed and sacked, the uniforms of the shah’s supposed “Immortals” lying on the ground, abandoned in utter panic.…