From Westwood & Simpsons' The Lore of the Land: A Guide to England's Legends:
The tradition concerns a mysterious, luck-bringing Queen Rat. This was a supernatural creature whose true appearance was that of a rat; she would follow the toshers [sewer workers] about invisibly, as they worked, and when she saw one that she fancied she would turn into a sexy-looking woman and accost him. If he gave her a night to remember she would give him good luck in his work; he would be sure to find plenty of money and valuables [among the garbage that ends up in the sewer] He would not necessarily guess who she was, for though the Queen Rat did have certain peculiarities in her human form (her eyes reflected light like an animal's, and she had claws on her toes), he probably would not notice them while making love in some dark corner. But if he did suspect, and talked about her, his luck would change at once; he might well drown, or meet with some horrible accident.
In Bookhounds, the Flusher (Contacts in the East End) is the theme-specific descendant of the tosher. Flushers know what's been found in the sewers, and who's been lost there, and they know the tangled labyrinth of tunnels beneath all London. The flushers will not talk to those they know despise them … although their sergeant, the Ganger, might unbend for a good reason. Especially if they've seen something Down There that you can show you know something about.
As with most things to do with the Victorian poor, Henry Mayhew is the most useful source.
Were it not a notorious fact, it might perhaps be thought impossible, that men could be found who, for the chance of obtaining a living of some sort or other, would, day after day, and year after year, continue to travel through these underground tunnels for the offscouring of the city; but such is the case even at the present moment … Many wonderous tales are still told among the people of men having lost their way in the sewers, and of having wandered among the filthy passages - their lights extinguished by the noisome vapours - till, faint and overpowered, they dropped down and died on the spot. Other stories are told of sewer-hunters beset by myriads of enormous rats, and slaying thousands of them in their struggle for life, till at length the swarms of the savage things overpowered them, and in a few days afterwards their skeletons were discovered picked clean to the bones …
They carry a bag on their back, and in their hand a pole seven or eight feet long, on one end of which there is a large iron hoe. The uses of this instrument are various; with it they try the ground wherever it appears unsafe … Should they, as often happens, even to the most experienced, sink in some quagmire, they immediately throw out their long pole armed with the hoe, which is always held uppermost for this purpose, and with it seizing hold of any object within their reach … without the pole, however, their danger would be greater, for the more they struggled to extricate themselves from such places, the deeper they would sink … in addition to the long hoe already described [they equip themselves] with a canvas apron, which they tie around them, and a dark lantern similar to a policeman's [with a lens that could be restricted] this they strap round them on their right breast, in such a manner that on removing the shade, the bull's-eye throws the light straight forward when they are in an erect position, and enables them to see everything in advance of them for some distance; but when they stoop, it throws the light directly under them, so that they can then see any object at their feet.
Athletics 9, Health 5, Scuffling 10
Hit Threshold: 6 (small and nimble) or 4 (human form)
Alertness Modifier: +1
Stealth Modifier +3 (rat form) or 1 (human)
Weapon: -2 (bite, rat form), -1 (bite, human form), claws +0 (human form)
Special: a bite from a Rat Queen does not heal. In game terms, the Health damage heals but the wound still seems recent and will not scar or scab over. This is because the Queen uses these bites to mark her prey, either so she can give her victim good luck, or so she can track the ones she hates. Any bitten victim can be tracked unerringly by the Queen, and her Alertness and Stealth modifiers increase by 2 against those victims.
Armor: none. However a Rat Queen killed, or buried, in London's sewers or the river Thames will re-form one month to the day after being killed. To ensure she doesn't come back, it's best to bury a Rat Queen far from London, or at least to burn the remains and scatter them to the winds.
Stability: +1 in rat form, none in human form unless the person seeing her knows what she really is, in which case loss is +1.
Magic: 8, refreshed each day at sunset.
Spells: Rat Queens are often friendly with ghouls, and many know how to Call/Dismiss Mordiggian. Rat Queens of this type can also summon ghouls, on a 4-point spend per ghoul summoned.
Create Hypertime Gate is also a common Queen trick. All of them know Dominate, and are very familiar with Idiosyncratic Magic. This last is why so many would-be sorcerers seek them out, often at their peril.
A 2 point Magic spend summons one Rat Thing, or a 20-strong rat swarm. Up to 6 points can be spent this way in one scene.
While in the sewers, a Rat Queen can summon dead toshers from the muck where their forgotten bones sank. Treat as zombies for combat purposes, and for each 1 Magic point spent the Queen gets a tosher. They all have weapons, their hoes, which strike for +1.
Rat Queens know where all kinds of peculiar things are hidden, lost, or abandoned. Seekers after treasure, or just a back way in to some well-guarded sanctum, can bargain with the Queen, but her price is usually very high indeed.
Some Bookhounds claim a Rat Queen can, if she wishes, give their store good luck. A Windfall can be had, if the Bookhounds meet her terms. Of course, her enmity works the other way, and any Bookhound store on the Queen's bad side suffers a Reverse. This is why some nervous Bookhounds frequent East End and riverside pubs; they hope to catch the Queen's roving eye.
Killing and properly disposing of the body of a Rat Queen dispels all of her magical effects, for good or ill. So Windfalls vanish, as well as Reverses. However if it ever becomes known who did it, other Rat Queens, Rat Things and ghoulish allies will take vengeance against the killers.
While Rat Queens don't lead cults, they have many friends in the East End and sewer Flushers, and can call on these friends for any aid short of actual combat. Many of these friends have been the Queen's lover in the past, and bear her bite mark; a useful identification aid for Bookhounds trying to work out who to trust.
Night's Black Agents Variation: though Rat Queens can still be found in the East End, and particularly Docklands, the area has transformed since Mayhew's day, and so have the Queens. Now they can often be found in gastropubs, or the latest two-or-three star restaurant, or some banker's multimillion pound den overlooking the shining City and the Thames. They move among the elite, and have become power players in their own right. Their ability to confer Luck makes them very popular creatures, and they trade on this, changing lovers every other week or so. Rats ride high, in this new London. In a Dracula Dossier game, Dracula long ago learned about the Rat Queens, but whether they became his Minions or remain a neutral supernatural power is an open question. If they did not become minions, they surely resent this foreign parvenu and can be persuaded to become temporary, fickle allies, with the right inducement. If they did, a Queen will be in charge of a London-based Node, perhaps a Satanic temple; they accept nothing less than dominance inside their territory, but aren't interested in anything outside London. In a NBA game without Cthulhu or related magic, assign two free and one other Renfield power to a Queen, and Aberrance 10.