"Of course," Sherlock says, evenly. He's certainly not to give away his own plans, his own conspiracies, but there was enough on public record to make chit-chat about.

"There was an explosion, even. There have been executions. If you want my advice, keep your head down and do as your told."

It was, of course, the exact opposite of the advice he would give, if every word they spoke wasn't being recorded.