A novel character emerged from the mists of Second Empire France and roamed the boulevards of Romanticism. This man was Baudelaire’s flâneur, but that’s not all he was. In depressing St. Petersburg, he was the anonymous hero of Dostoevsky’s Notes from Underground. In depressing Kristiania, he was the anonymous hero of Hamsun’s Hunger. He was Malte Laurids Brigge, lonely in Paris, in Rilke’s Notebooks, and he was Antoine Roquentin, lonely in fictional Bouville, in Sartre’s Nausea. After the Second World War, he fled the Continent and was spotted in England consorting with — and often confused for — a mustached man…