Poor John Watson is, of course, eventually going to learn that Sherlock faked his death.

When the show returns for a third series next year, Mark Gatiss has hinted that Sherlock’s faithful friend will probably be pretty mad when he learns what the master sleuth put him through.

Gatiss told the PA: “There’s certain things about [Conan Doyle novel] The Adventure Of The Empty House which feel set in stone because that’s how Sherlock comes back, but at the same time we feel free to invent and to introduce new stuff to it.

“I always found it a little unlikely that Dr Watson’s only reaction was to faint for instance – as supposed to possibly a stream of terrible swear words.”

Shooting on the third series will begin early 2013.