In the spring – already hot because this is southern Iran, and southern Iran is hotter than it used to be – I landed in the middle of the night at the tidy, unassuming Shiraz airport, along with a dozen well‑heeled westerners. We got off the plane – a Turkish Airlines Airbus, because our insurance companies had not countenanced our travelling by Iran Air – and joined the queue for passport control. I looked at my fellow travellers and thought I detected, over the natural melancholy of people who have been woken up at a cruel hour, a glitter of unease. We were a party of mostly Brits, Americans and Australians – you could hardly have devised a rainbow more likely to arouse the suspicions of the Iranian authorities – and we were entering a country that we had heard vilified all our adult lives, and to which our respective governments counsel against all travel unless absolutely necessary. Inside the airport, the members of the group shuffled uneasily forward to show their passports to young, unshaven men in bottle-green uniforms, or to their female counterparts, hooded and pale under the strip lighting. But these immigration officials turned out to be…