OUT of all the weeks in the Skripal Affair, this has been one of the strangest. The more you think about the details, the more bizarre the TV interview with suspects Ruslan Borichov and Alexander Petrov really is. The fact that they came to see the Cathedral but accidentally ended up in the opposite direction by Sergei Skripal’s house. The fact that these erstwhile survivors of a Russian winter were beaten back by the impenetrable Salisbury slush. The fact that the precise height of Salisbury Cathedral is one of world-renown (I think that might have been the only actual fact in the whole sorry episode).

If it feels as though the boundaries between truth and fiction have become blurred, spare a thought for those in the city whose trade is to write about this sort of thing. Next week sees the publication of Sleepers, the latest novel by Salisbury-based thriller writer Mark Dawson. Mark, as I have mentioned before, is something of an indie-publishing superstar. His books don’t appear in the shops, but have sold a remarkable two million copies worldwide. Writing his latest book, however, his plots and events in the city started to overlap.

Mark’s premise for his new novel seemed a good one when he started it at the beginning of the year: a story inspired by the 2006 attack on Alexander Litvinenko. His story started with a retired Russian spy living in Salisbury, who is killed by a pair of assassins. But then, as he was writing the story, the Skripal events began to unfold, near to Mark’s office. Everywhere Mark went, it felt as though the story was following him: he was in his office, working on the Sunday that the Skripals were taken ill; his regular dog walk through the hospital grounds was interrupted by the world’s media; he was walking past the bins on Catherine Street when the police pulled up to seal them off and search them. On one sunny day, his daughter had a school picnic in Queen Elizabeth Gardens; the next, it was closed by police.

How do you respond to all that as a writer? Mark rewrote, changing the location of the novel from Salisbury to Southwold. As the title of the novel suggests, his assassins were sleepers, embedded in the UK rather than a pair of weekend tourists. And unlike Ruslan and Alexander, they were somewhat more successful in their aims. When I saw Mark last week, he described Skripal’s attackers as ‘really s**t assassins’ – an assessment that their subsequent TV appearance has only gone on to confirm.

Sleepers by Mark Dawson is out on September 30. Mark is at Salisbury Literary Festival on Friday, October 19.