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. The reader half expects him to uncover a plot to sell Britain to China, and then be chased by soulless technocrats through moonlit moorland.

On one level, it didn’t work: when he stood for the leadership against Johnson and others, he seemed too intense, too eccentric. But maybe the party wasn’t ready for him. Maybe it had to consummate its relationship with Johnson, to drink the clownish cup to the lees, before it was ready for a rethink.

Stewart presents himself as the only serious moral foil to the Cameron-Johnson era. He protests too much, one feels at first. He sounds rather precious and preening, when he complains that Cameron failed to help him get elected – especially when this Old Etonian derides Cameron’s reliance on Old Etonian advisers. But gradually Stewart’s case is persuasive: Cameron and chums do indeed seem too enamoured of the game of politics, and to lack proper moral engagement.

Is Stewart’s moral earnestness rooted in religion?

As a minister, especially prisons minister, he gets stuck in with notable (perhaps ostentatious) energy. It’s not enough to be a smooth policy wonk, one must serve with almost priestly dedication, and share in the sufferings of the underprivileged. In a sense his most interesting stylistic rival is Gove, a policy wonk with a sort of priestly air. Ultimately, Stewart implies, Gove’s performance of high duty is a ruse, a screen for deep plotting.

Is Stewart’s moral earnestness rooted in religion? It’s strange that the reader is left unsure. In interviews he has quietly mentioned that he is an Anglican, but in the book there is no clear reference to this that I noticed. He mentions going to church at one point, but only to tell us that he’s accosted by an angry Brexiteer.

Why such religious reticence? Imagine a memoir by Rees-Mogg in which he didn’t mention his Catholicism, or one by Kate Forbes in which she didn’t mention her evangelicalism. Why shouldn’t an Anglican politician mention his form of faith? Maybe it would have helped him, by linking his moral earnestness to something wider, shifting the focus away from his personality, and his odd imperial hinterland.

At one point he likens Johnson to a ‘libidinous pagan poet’ rather than a self-disciplined senator. Could he have gone further, and denounced the Tory party’s drift away from its moral and religious traditions? It would have seemed too preachy and priggish, you might say. But he already has that air, so it might, in fact, have given him substance. He should have said that the Tory party needs a strong conception of the common good, which is probably religious, if it is not to become the playground of slick show-offs, ironic clever-clogs, dodgy brainiacs, witty shallow bullies. He still should.