The building known as John Knox’s House, in Edinburgh, has only a tenuous connection with John Knox, who may not have lived there at all – or, at most, only for the last few months of his life. But the tradition linking it to the great Protestant reformer proved its salvation when it was threatened with demolition in 1850. To pull down Knox’s house in Edinburgh, it was argued, would be an act of cultural vandalism comparable to destroying Dante’s house in Florence or Titian’s house in Venice. Only a few years earlier, in his lectures On Heroes, Hero-Worship and the Heroic in History (1841), Thomas Carlyle had hailed Knox as the founding father of modern Scottish history, without whom there would have been no James Watt, no David Hume, no Walter Scott and no Robert Burns.

Knox’s House makes a brief appearance in Ian Rankin’s novel Resurrection Men (2002), as Detective Inspector John Rebus and a group of his fellow cops weave their way unsteadily down the Royal Mile on a late-night pub crawl. As they pass Knox’s House, one of them stops and gestures drunkenly towards it: “This is everything that makes us what we are! That’s history . . . . Our history”. Rebus “wanted to say something about how women and Catholics might not agree. He didn’t know much about John Knox, but he seemed to recall the man hadn’t been too keen on either group”. Meanwhile, his companions keep up an irreverent chorus in the background. “Anyone else’s mum bring them here?” “I came with a school trip.” “Fucking boring it was too.”

Knox, it would seem, has gone from hero to zero. The extravagant adulation of him as the Scottish Luther – Carlyle’s “Hero-priest”, who “wears out, in toil, calumny, contradiction, a noble life, to make a God’s Kingdom of this Earth” – was very much a phenomenon of the nineteenth century, reinforced by the schism within Scottish Presbyterianism after the Disruption of 1843. Venerating Knox as the champion of civil and religious liberty was a way for the Free Church – which bought Knox’s House in 1868 and turned it into a museum – to lay claim to Knox’s legacy. But with the steady decline of Protestant Scotland, Knox has gradually diminished to an isolated, sectarian figure, leaving many Scots, like Rebus, suspicious of what he represents or simply uncertain about what…