Alexandre Jardin, a top French novelist, has blamed his grandfather for the biggest wartime round up of French Jews, igniting a literary and family row as historians and critics trade blows over whether he has re-written history to suit the story. Until now, Mr Jardin has been known for a string of fluffy, feel-good bestsellers in which he often makes light of his family.But in his latest book, Very Nice People, out next week, he launches a scathing attack on his grandfather, Jean Jardin, who was chef de cabinet of Pierre Laval – prime minister of the collaborationist Vichy government – from April 1942 to October 1943.Historians and writers – including Alexandre’s own father – have concurred that Jean Jardin was a relatively minor figure in the Vichy government. He was pardoned of any wrongdoing after helping the Resistance later in the war from his base in Switzerland. He went on to be a financier and was close to several top politicians, including François Mitterrand, the former president. He was also a friend of Coco Chanel.But Alexandre Jardin insists these accounts are indulgent, and that his grandfather was instrumental in the Vél’ d’Hiv’ roundup, in which around 13,000 French Jews, including more than 4,000 children, were arrested in Paris and placed in a bicycle racetrack and the nearby Drancy internment camp. Most died in Auschwitz.