In 1915, and for the next decade or so, P.G. Wodehouse's fictional world mushroomed within his imagination. His best-known creations, Jeeves and Bertie, arrived in that year, as did Lord Emsworth and many of the Blandings circle; the Oldest Member teed off in 1919; the Drones Club threw open its doors in 1921; a new, thoroughly improved Stanley Featherstonehaugh Ukridge returned to the fold in 1923, and Mr Mulliner sipped his first hot scotch and...