There was one story that Dr John Watson, biographer of Sherlock Holmes, did not reveal, in deference to his friend’s wishes. In The Adventure of the Sussex Vampire, first published in the January 1924 issues of The Strand Magazine in London, Arthur Conan Doyle writes that Holmes has received a letter from Morrison, Morrison and Dodd, a firm of solicitors. The letter says that they have recommended a Mr Ferguson, who has asked for their assistance in a matter concerning vampires, to contact Mr Holmes, adding at the end ‘We have not forgotten your successful action in the case of Matilda Briggs’. Holmes says to Watson, as an aside:
Matilda Briggs was not the name of a young woman, Watson, … It was a ship which is associated with the giant rat of Sumatra, a story for which the world is not yet prepared.
How the ship, the rat, and the Indonesian island are related is left tantalisingly in the air. There are indeed giant rats in Sumatra, and the New York Times told us a lot more about the matter in 1983. Perhaps the creature was an unusually large specimen of the common ship rat (Rattus rattus), that was used in a plot, foiled by Holmes, to spread the bubonic plague through London. Alas we will never know since Watson arranged that his notes on the bizarre story of the giant rat should be held in the vaults of a London bank in perpetuity.
This has not however prevented innumerable books, plays and films being produced taking the story of the Giant Rat of Sumatra one step further, including:
- In Pursuit to Algiers, a 1945 Holmes film starring Basil Rathbone and Nigel Bruce, Watson tells the story of the Giant Rat of Sumatra to an audience on board a ship.
- The Talons of Weng-Chiang, a 1977 Doctor Who TV serial set in Victorian London, in which the hero (dressed in deerstalker, accompanied by a medical doctor with a housekeeper Mrs Hudson) confronts a giant rat in the sewers of London
- Sherlock Holmes and the Giant Rat of Sumatra, a 2010 novel by Paul D Gilbert, has Holmes investigating the mysterious reappearance of the long-overdue clipper Matilda Briggs.
The largest rat in Sumatra is the Mountain Giant Sunda Rat (Sundamys infraluteus) which is 9 to 11.5 inches long, excluding the tail, and it weighs 230 to 600 grams, which makes it about twice the size of the common rat. Whether this is the rat to which Holmes was referring (or Doyle was thinking of) we don’t know. But if the public were to hear that rats of this size, carrying a deadly plague, were scuttling around under the streets of London, it would of course induce the greatest panic. And so, it must remain a story for which the world is not yet prepared.