The Decline and Fall of the British Empire, By Piers Brendon

In recent years the British Empire has been the subject of fresh scrutiny and, in the case of some prominent historians and politicians, rehabilitation. Now Piers Brendon has brought his own sharp eye to the debate, with a narrative spanning five continents and more than two centuries: from the surrender of the British to the American forces in 1781, up to the handover of Hong Kong to China in 1997. It's a colossal theme at the time of the British Empire Exhibition at Wembley in 1924, there were 58 countries in an Empire of 400m. people.

Brendon's title is a deliberate echo of Edward Gibbon's The History of the Decline and Fall of the Roman Empire. Its relevance lies in the analogies perceived by Britons, who found the key to understanding their Empire "in the ruins of Rome". He insists that he is not setting himself up as a rival to Gibbon. Rather, he is trying to do for the British what Gibbon did for the Romans "to give the big picture vitality through abundance of detail, telling the imperial story in terms of people, places and events". This he does superbly: with brio and panache and, often, a mordant wit.

He argues that it was a liberal empire, founded on Burke's doctrine that "colonial government was a trust" for the benefit of subject people until they attained their birthright of freedom. Many British empire-builders took this civilising mission seriously, supported by District Officers with a keen sense of duty and justice. But in terms of a moral audit, the balance-sheet in this book tilts heavily the other way. Drawing on recent histories of slavery, the Indian Rebellion of 1857 and the Mau Mau crisis in Kenya, Brendon sets out these brutal episodes in their full, ghastly colours. He also recalls forgotten atrocities. To crush rebellion in Kandy in 1818, the Governor of Ceylon led a force killing more than one per cent of the population.

As with Gibbon, the "daemon" is in the detail. When British troops plundered the Chinese emperor's Summer Palace in 1860, they stole a Pekinese dog which was presented to Queen Victoria, "who called it Looty". Between 1930 and 1940 in the copper belt of Northern Rhodesia, the British took 2.4m. in taxes and gave a mere 136,000 for the development of essential services.

At times, the text reads like a boys' comic from the Fifties. When the British withdrew from Aden in 1967, the last man to board the RAF Britannia "climbed the steps backwards, holding a Walther PPK pistol in his hand". But this adventure is given an adult perspective. Brendon quotes a judgment by the High Commissioner's legal adviser: "our whole exercise, from 1799 to 1968, [was] one of selfish power politics".

Mindful of what happened to their Roman precursors, the British tried to resist imperial doom. But in vain. Although Lutyens designed New Delhi to symbolise the "lasting supremacy" of the British Raj, the new capital was inaugurated "just as the Raj entered its terminal stage of decay". When Nasser seized control of the Suez Canal in 1956, Eden and Macmillan feared that unless they met the challenge, "Britain would become another Netherlands". As it turned out, Britain's Suez adventure undermined even further its position as a world power the imperial baton had passed irrevocably to the US.

In a book of such epic proportions, there are bound to be omissions, as Brendon readily acknowledges. For one thing, there are few women; little is said about the "official mind" of the Empire as it functioned in Whitehall. Also absent are the views of the colonised. But this is a difficult area to research, precisely because of the inequalities of empire: the sources available are largely the records of those who ruled.

As with Gibbon's Decline and Fall, the "great tapestry" of Brendon's book "is distinguished by its threads". Consequently, most readers would be hard put to reduce the meaning of the British Empire to any glib or simple judgement. This is a real achievement and an important one. For the imperial drive wears many labels, as we see in Iraq today and it sows dragons' teeth. "The spirit of imperialism is not dead," warns Brendon: "it haunts the modern world and its manifestations are legion".

Susan Williams's 'Colour Bar' is published by Penguin

Jonathan Cape 25 (793pp) 22.50 (free p&p) from 0870 079 8897