HarperCollins £18.99 pp288

When Enoch Powell made his notorious speech in 1968 foreseeing the river Tiber foaming with blood, he caused outrage in liberal hearts. Not only had he warned of an unthinkable catastrophe that could arise from unbridled immigration, but he had done it by quoting a Roman poet writing 2,000 years ago. This was simply not on. The days when politicians spouted epigrams from Virgil at each other went out, it was affirmed, with Gladstone. Latin was the secret code of the nobs, learnt the hard way in places such as Eton and long overthrown by a new world encapsulating their thoughts in good old vernacular English. And now, nearly 40 years on, here comes another politician not only writing a book on ancient Rome, but having the chutzpah to try and show us what we could learn from the Romans about making one Europe from a plethora of discordant parts.

What’s more, he makes a pretty good fist of it. Had he not already shown his paces in a clutch of métiers — MP, columnist, editor, television pundit and wit — he would have made an admirable Latin beak. He knows just how to keep his class on the edge of their seats with a hail of modern allusions. His metaphors glitter; his similes soar. He can grow quite lyrical when roused on his passion for Rome and the Romans. “It is the memory of a peaceful and united continent that is so appealing,” he enthuses. “It tolls to us across the ages, like the church bell of a sea-drowned village. It is like a memory of childhood bliss.” It was the Latin language that acted as cement to this arcadia, “with its quality of clicking together sweetly and unforgettably like perfectly dressed blocks of stone”.

In that dawn, then, ’twas bliss to be alive — but not always. Sometimes the natives were restless. The Germanic tribesmen, for example, whom the Romans thought they had subdued, were in the habit of emitting a bloodcurdling war whoop called the baritus. When they all did it together, it produced “a roaring noise like a chorus of Rolf Harris digeridoos”. They did it when they fell on Publius Quintilius Varus, toady, careerist and, as Johnson tells us, “ monumental cock-up artist”. The Romans lost three legions that day. PQV had no choice. He buried the handle of his sword in the ground, then ran up to it “with the determination of a Twickenham try-scorer and skewered himself through the guts”. When the emperor Augustus heard about it, he bashed his head against the wall and refused to shave for weeks. Again and again he moaned the name of his dim-witted chum. “Quintilius Varus,” he intoned, thudding the imperial bonce against the jamb, “give me back my legions.”

Despite the odd disaster like that, the Romans did a neat job of running the greatest empire the world has ever seen. The mastermind behind it was that same Augustus who had wept for his legions. Brilliant, subtle, complex, calculating, slight (he stood only 5ft 6in), he did it by legerdemain. He was emperor 41 years, and in the end he was god. His cult was taken so seriously that priests would have his face sewn on the tops of their cowls “just as the women of Malawi would have the face of Hastings Banda emblazoned on each buttock”. Johnson goes into the great Roman theatre at Orange in France, looks up at the proscenium “and there he is, arm aloft like Shane Warne doing his flipper, effulgent in marble and larger than life”. By the end of his reign, the head of the emperor was more pervasive than Mao’s in China. Sophisticated families had him in their dining rooms: “Imagine the frisson of horror if you went to dinner in Islington and looked up to see a marble rendition of Blair or Thatcher.” You’d think it was a joke; but to the Romans it was drop-dead serious.

Some passages (such as the steamy romance of Antony and Cleopatra) have been so expertly filleted by Shakespeare that they can seem over-familiar. Even here, Johnson is never dull; he goes to visit the spot at Actium where the doomed lovers “did some last-minute Taylor-Burton smooching before embarking”. He sees how hard it is for us to emulate Rome’s achievement in running 100m people spread over what are now 30 nation states “like a gigantic Moulinex”. He accepts that Europe will never recapture that huge and peaceable unity of races and nations “with the face ofevery citizen turned like a sunflower towards the political centre”. But he believes we are fated never to stop trying.

Exercises in likening then to now are invariably doomed to falter at the last hurdle. As Louis MacNeice, teaching the subtleties and ironies of Ancient Greece to students, concluded: “And how can one imagine oneself among them / I do not know / It was all so unimaginably different / And all so long ago.” Not so long as all that, though, nor so different, seen through the quick-silver mind of an entertainer such as Boris Johnson.

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