For those not familiar with it, Meepo’s Holmes Companion (HC) is a small supplement for Holmes Basic D&D that expands the original rules from level three to level nine. It was meant to give referees a simple but complete OD&D-based dungeon-crawling game, and it certainly does that in spades.
The Holmes companion was created and shared freely, way back at the dawn of the OSR, in early 2007 (the first editions of BFRPG and OSRIC had just been published in 2006). Thanks to the persistence of Forums like Dragonsfoot, you can still read about it.
From the last of those links, in April 2007, by the author:
I bought my White Box last year and was instantly smitten. However, I ended up with Holmes in the long run for two reasons:
1) I disliked having everything spread through so many volumes. Greyhawk made so many changes as well, that I wanted some consistency within my rules set. Granted, I had to remove a couple of weird elements (like the “dagger-twice per round” rule) and add my own 4 page document to expand on Holmes, but I did it strongly inspired by what was already in place with OD&D. To me, it is now the perfect version of the D&D game.
Since Holmes was originally based on OD&D, up to and including the Greyhawk supplement, it seems sensible that if you wanted to expand Holmes, you should work back towards that first incarnation of D&D. This is what Meepo did, and in only four pages, showing that not much was necessary.
As noted above, the HC gets rid of the dagger attacking twice-per-round rule, and adds a few other common-sense house rules. There is a small damage bonus for Fighters with above-average STR, an AC bonus for Thieves with good DEX scores, and simple two-weapon fighting and two-handed weapon rules.
It doesn’t include full saving throw or attack tables, referring instead to the monster attack matrix on page 19 of the Holmes rules, and it shows saves as a simple bonus to all save types from level three. Holmes already includes loads of higher-level monsters, so there is no reason to add to the bestiary. Spell descriptions are kept short, again like OD&D.
In the end, four pages seems perfect for this. The HC is not trying to make a whole new game, it just expands and fixes the important bits. I like that it’s short enough to print out and keep with your reference sheets/screens as you play. There are lots of other Holmes supplements, but this one is the shortest I know of.
If you’re interested in playing Holmes, or if you just like to read other people’s house rules, download the Meepo Holmes Companion and give it a look (there is also an archive.org copy from the author’s original site, now offline).