Can a dose of moral earnestness revive Tory fortunes? This is the question raised by Rory Stewart’s recent memoir, Politics on the Edge: A Memoir From Within, which sits on top of the bestseller charts more than three months after it came out. Another question the book raises is this: is Stewart’s brand of moral earnestness the right one? His politics is rich in old-world honour, like that of a John Buchan hero.