TO UNDERSTAND WHAT had been destroyed by the First World War, F. Scott Fitzgerald wrote, “you had to have a whole-souled sentimental equipment going back further than you could remember. You had to remember Christmas, and postcards of the Crown Prince and his fiancée, and little cafés in Valence and beer gardens in Unter den Linden and weddings at the Mairie and going to the Derby and your grandfather’s whiskers.”

The long hot summer that preceded the outbreak of war in 1914 became, in retrospect, a time of unimaginable calm and naivety, the dying moments of the old world, before Europe was churned into a charnel house. That extraordinary cusp-moment in history provides the hinge for Pat Barker’s new novel Life Class, a triumphant return to form and to the period evoked so superbly in her Regeneration trilogy.

Paul and Elinor are students at the Slade School of Art in the spring of 1914, studying under the demanding Henry Tonks. Kit is a Slade graduate, well on his way to fame and fortune. All are immersed in their art, and in each other, flitting from the life class to the Café Royal. It is a fey and feckless time. Paul has an affair with an artist’s model, but his is a callow and shallow passion.

Barker’s first training was in history, and this gives her fiction such tensile strength. Her imaginary students are based, in part, on the artists Paul Nash, Christopher Nevinson, Mark Gertler and Dora Carrington. Her characters are real, but unconstrained by mere biography.

The only shadow over Paul’s self-absorption is his lover’s enraged and estranged husband, a former soldier, who stalks the couple, and savagely beats him up. The looming war is unobserved. It arrives casually, over the dinner table, in a remark made by Elinor’s father, a doctor: “We’ve been asked to clear the beds. Postpone nonurgent operations.”

All three artists are suddenly and cruelly forced to confront the conflict. For the ambitious Kit, a promising Futurist, war is a career opportunity; for Paul, a volunteer medical orderly in the Belgian Red Cross, it is the next stage in the jolting journey of his own art.

But Elinor refuses: she does not volunteer, or nurse, or follow any of the demands of women in war, but doggedly pursues her art – and tea with Lady Ottoline Morrell – in a way at once admirable and repellent. “If painting matters you have to give your life to it, and that’s what I’m doing.”

“Doesn’t summer seem a long time ago?” she writes to Paul, now submerged in the stench and the gore of Ypres. “When I try to look back all I can see is a huge blue-black cloud chasing its own shadow over the shining fields.”

In Life Class, Barker demonstrates her mastery of dialogue: the words unsaid are more telling than those articulated. The First World War, with its combination of brutality, formality and sexual alertness, is the perfect backdrop for her taut, unsparing prose: the unspoken amid the unspeakable.

At its heart, this is novel about honesty, about the demands of truth and beauty amid the moral-paralysing horror, and the dead weight of duty. In a shattering scene, the young medical orderly comes across a French mother, smothering to death her young son who has lost his limbs. Paul says nothing. Yet he also struggles to comfort a soldier with a self-inflicted wound, despite knowing that if he is cured, he will simply be put before a firing squad.

In Double Vision (2004), Barker addressed these dilemmas less successfully through a foreign correspondent of the modern age who described his role as: “Witnessing. Giving people the raw material to make moral judgments.”

In different ways, the three young artists in Life Class seek to bear witness. Paul paints what he has seen, carbolic acid in a gangrenous wound, the anonymity of a battlefront hospital. Back in London, now injured, he shows his work, including a young man with part of his face destroyed by a shell, to the formidable Tonks, who responds: “I don’t see how you could ever show that anywhere.”

“No, I know,” Paul replies. “But I wanted you to see it.”

The real Tonks (who became principal of the Slade in 1917) was a remarkable war artist: his paintings of men mutilated on the Western Front played a vital role in the development of plastic surgery and remain, as Barker notes in an afterword, some of “the most moving images to have come out of any war”. The fictional Tonks may be doubtful, but the real artist bore witness magnificently.

Throughout the novel (as with her earlier trilogy) runs a raw fury at the sheer thuggery of this conflict between civilised peoples, the brawling monster that strode into Europe one hot, peaceful summer, demanding to be heard, destroying the old world of tea and fine art and grandfather’s whiskers.

“War takes over all our lives,” Elinor declares. “It’s like a single bullying voice shouting all the other voices down.”

In the foetid trenches, the blood-slimed dressing station, or at the easel, the essential fight is against that dehumanising bully: that is the living – and resoundingly contemporary – lesson of Barker’s inspiring Life Class.

LIFE CLASS by Pat Barker

Hamish Hamilton, £16.99; 256pp

Buy the book here for the offer price of £15.29 (free p&p)

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