Stanley Johnson suggests his son, the PM, will easily deal with Iran because he is well acquainted with Persian history and knows all about kings such as Darius and Xerxes. But talking ancient history with Ayatollahs could have its problems. Here, for example, is what Herodotus (d. c. 425 bc) had to say about Darius.

Distantly related to the royal family, he served loyally under King Cambyses, at whose death in 522 bc a usurper took power. Darius plotted with six others to dethrone him, suggesting they should lie their way into the palace and kill him: ‘Where a lie must be told, tell it. Those who lie and those who tell the truth all have a similar objective, to gain advantage: same end, different means.’ They succeeded, and five days later discussed what form of government should ensue: democracy (accountable, rule under the law), oligarchy (best men to rule, not the mob), or monarchy (best man, avoiding factional strife)?

Monarchy won. They decided to choose the monarch by riding their horses to the edge of the city before sunrise, and the rider of the first horse to neigh after sunrise would win. Darius won by a trick: his horse was keen on a certain mare, so the groom tied her up at the agreed spot outside the city and then slowly led Darius’s stallion around and around her, finally allowing him to mount. In the morning at sunrise when Darius’s horse reached the point where the mare had been, he let out a great whinny and Darius became king. (The Tories should try it.)

Or the PM might chat about ancient Persian customs, on which Herodotus is eloquent: retaking drunk all decisions made sober (and vice versa); special dinners on birthdays (baking a whole ox, camel, horse or donkey); honouring their nearest nations, with respect decreasing as distance grew; enthusiasm for foreign customs (they learned pederasty from the Greeks), and much more.

Somehow one doubts the Ayatollahs would warm to this. Extoll(ah)ing the vast Persian Empire, begun by Cyrus the Great (d. 530 bc), stretching from Turkey and Libya to Pakistan, with its infrastructure, civil service, postal system, road-building and central administration, might make a safer bet.