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.

The reference to adventures that the good doctor never wrote down is one of the fun elements of the Sherlock Holmes canon.

As a Holmes reader I went through various phases – at first enthusiasm then irritation, and finally acceptance.
I will never be a Sherlockian¹, meaning, I can’t quote you chapter and verse of Holmes adventures, but I like the Sherlock Holmes stories – and I saw the Basil Rathbone movies before I read the books, so there.
When it comes to the written word, I detest doctor Watson with a vengeance, but I’ve come to appreciate and respect Sherlock Holmes: anyone that can stand Watson as a housemate for any length of time is quite obviously a better man than I am.

And then there is the Gian Rat of Sumatra, which has that nice pulpy feel to it that it’s really a pity the facts concerning the Matilda Briggs were never published. It is obviously Holmes moonlighting in the territories in which his counterpart Sexton Blake was more at ease.

There’s a number of Apocrypha, of course. I have here the ebook version of Richard L. Boyer’s The Giant Rat of Sumatra, part of the wonderful line The Further Adventures of Sherlock Holmes – because as an heterodox Sherlockian, I like Apocrypha, a lot.
And then there’s the worst special effect in human history the giant rat (of Sumatra?) that faces Tom Baker as a very Holmesian Fourth Doctor in Talons of Weng-Chiang.

But now I was researching the Giant Rat of Sumatra for Hope & Glory (because injokes are a good thing), and it turns out that there actually is a giant Sumatrese rodent, the Large Bamboo Rat, Rhizomys sumatrensis, that happens to be a big fat rat indeed- according to Wikipedia, individuals can reach lengths of nearly 50 cm (20 in) with a 20 cm (7.9 in) tail, and weigh up to 4 kilograms (8.8 lb).
And to add further pulp goodness to this fine specimen of Sumatran fauna, the thing is venomous, being the natural host for the Penicillum marneffei, a mold that causes fever and anaemia, and then death, in infected humans.
Isn’t nature wonderful?

And now, the true story of the Giant Rat of Sumatra, from the man himself… well, part of it…