The Great Outsider: David Lloyd George by Roy Hattersley

Protean is a grandiose word for reviewers to avoid; "variable, versatile, taking various forms", says the Concise Oxford. But consider David Lloyd George: nearly beaten to death for denouncing the South African adventure and Man Who Won the War; anti-imperialist and snapper-up of territorial bargains in 1919; Home Ruler and sender-in of the Black-and-Tans; land nationaliser and Surrey proprietor; Welsh Nonconformist and round-the-wicket adulterer; admirer of Keynes, admirer of Hitler; scorner of the Lords and Earl Lloyd George of Dwyfor. "Protean" hardly says it.

Churchill and Lloyd George are readily linked: grandchild of Blenheim Palace and nephew of a radical cobbler on the Lleyn peninsula - and quarrelling friends. Gaudy men, poster-painted, attention seekers, out for themselves and for great causes, everything by turns, nothing long, and always interesting. Of writing biographies of Lloyd George there is no end. However, at good but graceful length, Roy Hattersley may have written the book to wrap up argument. Another very intelligent politician, he stands at a cool distance but inside the arena, making sensible, ultimately melancholy, distinctions.

He dismisses LG's flaunting of his roots, but accepts as real his loathing of the inheriting rich - though not the enchanting, new-made rich. He had marked the effortless enrichment of rising estate values and just how poor decent people could be. Again, despite the cheerful sex, enough Protestant Nonconformity clung to him. Detestable drink was left to Asquith. The radicalism varied. Never that ardent a Home Ruler, twice he brushed away boundary plans confining Ulster to its narrow heartland: with what consequences we have seen.

The pre-war radical, says Hattersley, wanted to raise "the deserving poor". What he said about the Lords, "Five hundred men chosen at random from among the ranks of the unemployed," he meant. The sincerity bites the gloved hand. As Chancellor (1908-1915), the land campaign, national insurance and smashing their Lordships' House were in earnest; likewise the spitting, purple response. One Duke spoke of "getting Lloyd George and Churchill in among two dozen dog-hounds". Hated there and loved by radicals, he was happy.

Yet he was never a party man. The idea of coalition, bringing the ablest men together, would surface in pre-war friendship with the Tory FE Smith, re-writer of English land law. Before 1914, LG had talked of bypassing "the duffers" for a party of clever men, also of "strong government". Wartime coalition fulfilled this mental doodle. As Prime Minister, from 1916, he found Bonar Law - via Canada, an Ulster Protestant of the gloomiest sort, but unselfishly straight - his prop against resentful Tories. "I agree with you about dictatorship," Law told Walter Long. "This is essentially LG's government".

That had involved the fall of Asquith, whom Hattersley does not mourn. He had asked if three key Tories would join a Lloyd George government: "When a Prime Minister is driven to ask such questions, he is not destined to remain Prime Minister for long." He sums up without ceremony. "Asquith was an incompetent PM and fought an incompetent campaign to remain in office."

Real trouble lay with Kitchener, Haig and Robertson, duffers indeed, brutes too, whom no revision can mend. "Kitchener," said LG: "great driving force, but no mental powers... hard eyes, relentless". The Kitchener problem would be solved by HMS Hampshire, sunk en route for Russia in 1916. Lloyd George, scheduled for that trip, put it perfectly. "Poor K, at the best possible moment for the country, and for him."

Thousands of soldiers would also drown - in mud, at Passchendaele, 31 July 1917, about which the generals were indifferent. They were also stupidly unamendable. Passchendaele happened because Haig and Robertson were addicted to the frontal assault, the next push, the push after that, the final push. And it happened because the PM was afraid of them. The rotten, rational French favoured a defensive strategy until the Americans, persuaded by their own torpedoed shipping, should come.

Lloyd George agreed, but feared the other fight - in the war council. "Both have a considerable backing in the press," he wrote, "the Asquith group... Northcliffe... an incongruous combination, but too strong to challenge". For Hattersley, "This was an admission of pathological timidity". Incidentally, Haig would live to rage at his placing at the victory parade – "in the fifth carriage with a pack of foreigners".

Hattersley acknowledges the fire, wit, energy, flair, purpose and sheer difference of Lloyd George. But his nemesis and antithesis, Stanley Baldwin, had a point. The post-war years illuminate a governing flaw. Afraid of Tory clamour, he would be disloyal, dismissing colleagues like Edwin Montague, trying, however clumsily, to do enlightened things. Grasping Keynes, he would make Liberal economic policy brilliantly relevant. But the distrust he had created inhibited Ramsay MacDonald from embracing him (and Keynesianism). He would yearn for office when it was gone and pronounce Hitler a great man. Protean he was, but the flaw won.