Nicholls' other motive is to rescue him from Joseph Chamberlain's shadow. But for the scandal, he argues, Dilke would have emerged as Gladstone's successor, and could have remodelled the Liberals into a progressive Radical party fit for the modern, almost-democratic era, thwarting the need for a separate Labour party.
These are big claims, but they provide a valuable perspective, putting Dilke instead of Chamberlain in the limelight. Of the two, Dilke was the younger but the first to arrive at Westminster. He had been born into a wealthy London family. His claim in old age that "I have known everyone worth knowing from 1850 to my death" was not that preposterous. He travelled extensively. In America and Australasia he saw democracy and a republic first-hand. He wrote a political travelogue which made his name.
When he became MP for Chelsea, aged 24, in 1868, several strands of his Radicalism were already in place: his belief in democracy, social, education and land reform, and his leanings towards republicanism. Less usual, for a Radical, were his Anglican roots and commitment to vigorous foreign policy. The alliance with Chamberlain took off in 1880, when, after a tussle with Gladstone (who at 71, they reckoned had not long to last), the pair joined his government. As under-secretary at the Foreign Office Dilke had the less prestigious job, but he did it impressively. And, through birth and tact, he was able to get on with Gladstone and the Whig grandees in a way that Chamberlain, the aggressive, self-made man from Birmingham, never could. The intense, ambitious nature of their friendship is well conveyed, with effective use made of letters and the grumbling, exasperated notes they passed in Cabinet.
Unlike Chamberlain, Dilke would have stood by Gladstone when the Liberals split in 1886 over Irish Home Rule, had he had the chance. But in 1885, Virginia Crawford - the sister of his brother's wife - named Dilke as co-respondent in her divorce case, and, though the adultery was unproven, he was obliged to withdraw from public life. The political result was a Liberal party more Radical than ever, still led by Gladstone, with both Chamberlain and Dilke outside it. 1886 was a truly terrible year for Dilke, as he experienced the destruction of his reputation, the rupture of his party, his defeat at Chelsea, and the end of his closest political friendship.
In 1892, Dilke returned to politics, as MP for the Forest of Dean until his death in 1911, and devoted himself to advancing social reform. He encouraged the growth of the Labour party, but remained an extreme Radical, not a Socialist. On some issues - women's suffrage, contraception - Dilke was years ahead of his time.
This biography achieves what it sets out to: it is a very full, considered account. But it is essentially a political life: Dilke's wives and son have bit-parts, and when it gets to the scandal, the cast is so unfamiliar you don't care who did what. The book rescues Dilke from a hoary old caricature, and gives him many serious dimensions, yet curiously - maybe aptly - it does not reveal the private man.