At half past one in the morning of Tuesday 19 July 1898, passengers on the cross-Channel steamer from Calais to Dover might have observed a solitary middle-aged man standing on the deck, gazing steadfastly at the sleeping port as the boat pulled out into open water. He was visibly moved and after a few minutes his eyes began filling with tears. The breeze got up, under a covering of cloud across a calm sea, but though he had brought no overcoat with him he stayed where he was until the glimmer of dawn dimmed the gas lamps along Dover’s harbour front. The traveller was singularly unprepared for the landfall he was about to make. He knew almost no English and had embarked on the journey without a change of clothes or toilet articles. Managing to reach Victoria by train, he asked a cabby to take him to the Grosvenor Hotel. The man was pardonably surprised, given that the hotel was a matter of metres from the station, but deposited his fare at the front steps anyway.

Things had been different on Emile Zola’s first visit to England five years previously, when he arrived as the honoured guest of the Institute of Journalists, whose annual conference was taking place at the Crystal Palace. Although some of his novels, such as Nana and Thérèse Raquin, had been excoriated by the British press for their nauseating obscenity and dangerous influence on impressionable readers, the doyen of the French naturalist school was on that occasion whisked from a Guildhall banquet, lunch at the Athenaeum and oysters at the Café Royal to Drury Lane Theatre, the French Hospital and the Greenwich Observatory. Oscar Wilde, practised schmoozer of the famous, sent a basket of flowers for Madame Zola, the National Society of Teachers of French gave a champagne reception and the novelist took a turn around the House of Lords, which reminded him, not altogether agreeably, of the Académie française.

The Zola who fetched up in London in the summer of 1898 was a lonely fugitive from justice. His polemic J’Accuse…!, published in Georges Clemenceau’s left-wing newspaper L’Aurore, had fearlessly condemned the military court proceedings in the Dreyfus case, which was at the time tearing France to pieces. For denouncing the fraudulent basis of the two espionage trials that resulted in Captain Alfred Dreyfus’s expulsion from the army and imprisonment on Devil’s Island, Zola was deemed a criminal, guilty of libelling a public institution, which entailed a fine of 3,000 francs and a year’s jail sentence. Self-imposed exile seemed a more sensible option than this kind of martyrdom, but he boarded the Calais boat train with the bitterest sense of his country’s ingratitude. Michael Rosen’s lively and thoughtful analysis of the whole episode emphasises the novelist’s anguished bewilderment at the way in which France, by the very act of persecuting him for truth-telling, seemed ready to betray its finest traditions of rational discourse and civilised dissent. ‘To think’, he exclaimed, ‘that after a lifetime of work, I would be forced to leave Paris, the city which I’ve loved and celebrated in my writings, in such a way!’

Once across the Channel, however, Zola generally avoided attempts by British journalists to glamorise his victimhood. Inspiration for his new novel, Fécondité, came more easily to him in the anodyne dullness of a Surrey suburb than in the Grosvenor Hotel. First of all he rented Penn, a house in Weybridge, at five guineas a week, then shifted quarters to the Queen’s Hotel in Upper Norwood, maintaining a variety of incognitos as he went. Surprisingly, that summer of 1898 turned into something of an idyll. Zola bought a bicycle and rode it among the trim little villas and clipped holly hedges of Walton and Chertsey, taking his camera with him to snap anything from a busy high street or a herd of cows to road sweepers and bobbies on the beat.

Life was further sweetened by the arrival of his mistress, Jeanne Rozerot, with their daughter and son. The visit was arranged by his wife, Alexandrine. Resigned to her husband’s divided affections, she assumed the role of manager and legal representative during his absence in England. ‘I had little more to do with my sad existence’, she declared, ‘than to do good things for those I love.’ This was the ultimate act of self-sacrifice. Ensconced at Weybridge, Rozerot and the children joined gamely in the bike rides, took a trip to Windsor Castle and came to share Zola’s loathing of British cuisine. Why, he moaned, was everything unsalted? Why were the vegetables cooked without butter, the beefsteaks garnished with something called ‘gravy’ and the fruit tarts served hot?

Friends worried that Rozerot’s presence might damage his reputation, not merely among the Surrey bourgeoisie but also, more importantly, with a powerful Protestant echelon in France sympathetic to his campaign to exonerate Dreyfus. In Paris sales of his books plummeted, a further libel case threatened to cost him 40,000 francs and he was stripped of the Légion d’honneur. In Britain, on the other hand, he was becoming something of an adoptive national treasure. Crowds flocked to inspect the waxwork of Zola at Madame Tussaud’s. The Manchester Guardian praised his dogged courage, the Daily Chronicle saw him as embodying the finest of French values and The Times, portraying the original court case against Dreyfus as an intellectual treat for the educated, proclaimed that ‘he will be honoured wherever men have free souls’.

The Disappearance of Emile Zola honours its hero not only for his fortitude, consistency and sense of purpose but also for the way in which J’Accuse…! and Zola’s related writings exposed the Dreyfus case as a stalking horse for anti-Semitism in its most virulently sophisticated form. From the ritual humiliation of Captain Dreyfus on the parade ground it was a short step to Nazi round-ups, internment at Drancy or one of the other holding camps for Jews and a cattle truck to Auschwitz. Michael Rosen presents a plausible image of Zola as the harbinger, throughout his career, of a new kind of politics, internationalist in its struggles against poverty, injustice and racism. This book needed better editing – the author has an irritating habit of starting too many paragraphs with a date – but its evocation of a Britain confident enough to absorb and shelter a foreign dissident without the institutionalised hostility of visas or internment camps is, to say the least, timely.