As an alternate history set in the 19th century, there's a lot of historical details that went into making this book a good reflection - albeit distorted by 18 years of divergent history - of the times.
Chapter 1 - In the Queen's Gardens
[1] Lambeth Marshe is the historical name of the Waterloo borough. Which was the decisive Napoleonian Wars battle that has certainly not happened in this alternate history.
[2] The palace of Buckingham was originally purchased to be the residence of the wife of George III.
Chapter 6 - Day One
[3] Jacob's Island is described in Dicken's Oliver Twist as the worst slum of London.
[4] Pure is dog droppings, harvested for tanneries.
[5] A mudlark is someone who recovers trash washing out from the Thames.
Interlude - Exiled
[6] Charlotte Augusta, Princess of Wales, is the forgotten Princess of English History. Between bouts of madness, George III ordered his son to produce an heir, since none of his children had yet to sire a legitimate child. The future George IV managed to find a wife, made a single daughter, and basically said “sod off, I’m going back to my mistress”. Charlotte grew up, married to a dashing young man called Leopold – the future King of Belgium – and then… died in childbirth in 1817. The royal family had to scramble again to produce a new heir, finally producing an Alexandrina Victoria in 1819 – yes, that Victoria. In this alternate history, she’s still alive, kicking, unmarried yet, and they will probably end up talking about the Charlottean Era rather than the Victorian one.
[7] This is a reference to the War of 1812. The causes of the historical war are heavily tied to the tripartite politics around France, England and the USA, which means that in an alternate history where those things are upended, the nature and course of that war change completely. It started early, was waged using advanced technologies developed using the Labyrinth materials, and the British Empire was mostly prevented from supplying the local troops by having an active and hostile power on its shores. Where in original history the end of the Napoleonian Wars let them retake the upper hand in Canada, here, they had little choice but to admit defeat, and let the Three Northern Provinces add their stars to the Star-Spangled Banner.
Interlude - Wreckage
[8] Yes, he's that Charles Babbage, the engineer behind the original concept of the computer. The man was so smart, there's no way he wouldn't end up a Professional. He's relatively low rank despite having been there for years because he spends more time doing theory and studies than grinding levels.
Note that Ada, countess Lovelace, considered the first “programmer”, was born in 1815 and is unlikely to exist in this altered history.
[9] John Scott, Earl Eldon is also a real figure from the British Government of the time. Things have changed a bit with the cold war (probably now hot war again) against Napoleon and George III being more coherent and sane, but he's still Lord Chancellor as he'd be in normal history. He's basically the Winston Churchill of the time, utterly convinced that war is inevitable with all the rivals of the Empire, and the Brits might as well be getting on with the program.
Interlude - Versailles
[10] Napoleon Bonaparte is active and kicking ass in this alternate history. Rather than being defeated in 1815, captured and exiled in St Helena, he’s the absolute master of most of Europe, thanks to magical powers and material-enhanced technology. It turns out having landcruisers with internal heating helps a lot in waging a campaign in Russia, for instance.
Chapter 17 - Surrounded
[11] The Bloody Code was the basis of the English criminal system from the late 17th to early 19th century. It was named such because it featured the death penalty – by hanging, so not really “bloody” – for a lot of crimes, ranging from wearing blackface at night – a sure sign of bad intentions – to arson or forgery. Steal 50£ worth of goods? To the gallows with ye. The authorities considered crimes as a sign of laziness and sin and thought that harsher penalties would act as a deterrent, so executions were highly publicized.
By early 1800, it was on the decline and replaced with penal deportation. First, to the Americas, then, after the War of Independence, to the new penal colonies in the Pacific like Tasmania – then called Van Diemen’s Land – and mainland Australia, aka “New Holland”.
Interlude - The Frontier
[12] This is a "noble’s party". There are very few nobles in the Labyrinth: there are about 300 noble families in England at this point in time, and with one person in 380 being a Professional... that means very few nobles qualify. Louisa Grey is the daughter of Earl Grey (yes, the tea), former Secretary of State. Along with her is George Thomas Beresford, a former soldier, who mustered out of his cavalry regiment in 1803 (rather than being promoted, as in normal history) when he discovered he qualified for the Labyrinth. Charles Cecil Hope Jenkinson is the future Earl of Liverpool when his half-brother dies, a perspective he does not quite relish (as it will make it hard for him to go in the Labyrinth again). Last is Roland Howard, who is a fictitious twin brother to Henry Howard, 13th Duke of Norfolk.
Interlude - Hudson Bay
[13] The telegraph has yet to make its appearance (originally 1837, and the power sources from the Labyrinth are not a good substitute for electricity, so it might not even get invented for a while since you now have better engines and light and stuff!!!), so communication uses semaphore tower chains, a French invention (for Napoleon!) that was swiftly copied by many countries. The first semaphore chain in the USA was from Martha’s Vineyard to Boston in 1804. Its use here is slightly more extensive in this timeline vs the original 1818.
[14] Avery Randel is a fictitious sibling of John Randel Jr., the NYC surveyor that did the entire Manhattan grid for future development, emplacing cornerstones for each block (I think there’s two or three still visible there as monuments).
[15] John Tayler is the historical Lt. General for the state of NY in that era.
Chapter 23 - Reconnaissance
[16] Things that are cheap today would be unimaginatively expensive at the time. A labourer or farmer's annual income is around £15-20. Oakden, Jonas’s employer, is assumed to make over a hundred pounds a year profit from his shop (which is a medium store, has half a dozen apprentices, including Jonas).
The Morvell family, which are Ira's employers, are an upcoming merchant clan and probably make around £2,500-3,000 a year. It’s the entry ticket for the 1% of the era. In Jane Austen’s time (which is right now), about £1,000 a year was enough for a family to afford “three female servants, a coachman and footman, a chariot or coach, phaeton or another four-wheeled carriage, and a pair of horses”.
Interlude - Tier One
[17] John Henry Blackeye is a Lenape tribe member; not a real historical character, but very loosely based on Koquethagechton, aka White Eyes, the Lenape speaker that was heavily involved in the American Revolution.
Interlude - King's Palace
[18] Louisiana is named after King Louis XIV, part of New France. France lost nominal control of its territories in the mid-18th century, with the British gaining part of the territory and the Spanish crown getting the rest.
In True History, France managed a secret treaty with Spain in 1800, getting back ownership of the entire area, before selling it to the USA in 1803 to finance its wars. In this history, the secret treaty was never negotiated, and Spain lost to France a few years later. The USA seized control of the territory de facto, if not the jure, and has kept it since.
Interlude - Allure of the Greatest
[19] This is the “seventh” (and fictitious) Board of the Qing Empire. The Chinese empire operated under a meritocratic (with lots of creative cheating) system of civilian service based on multiple tiers of examinations, a complex ranking of bureaucrats (with 30 ranks of civil service). The top was the Six Boards or the Six Ministries: Rites, War, Personnel (bureaucracy), Revenue, Justice and Works. Those six ministries were under the authority of civilian bureaucrats (a Minister, several Vice-Ministers, and staff and the like).
[20] Princess of the Second Rank (meaning she's the daughter of a top-ranking consort, but not the Empress) Zhuangjin, is the one member of the imperial household to qualify as a Professional... or, in Chinese parlance, an Immortal Hero (it's xianxia time). In our history, she was headed to Mongolia in 1800, betrothed to a major Mongol Clan Prince. As originally Mongols themselves, the Manchu dynasty of the Qing kept intermarrying between the Imperial household and the backbone of their military. Now, instead of being stuck in some distant palace, she’s one of the Great Council, a sort of equivalent to the National Security Council, with a handful of members mostly from the Imperial household and family, serves as an alternate way of getting "important" stuff to the attention of the Emperor.
Chapter 33 - Her Royal Highness
[21] Breeching is an important step in a boy’s life in the 19th century. It is when he’s potty trained enough that you can replace the robes a boy wore until then by trousers.
Chapter 34 - Among Friends
[22] Mungo Park was a famous Scottish explorer, pioneer of the African interior. His books were highly influential and popularized the glamour of the mysterious hidden continent. He was trying to prove the theory of the Niger and Congo rivers merging at one point, and was killed in 1806 by a native tribe while doing so. The two rivers would ultimately prove to be distinct basins.
Chapter 35 - Inquiring Minds
[23] The Automated Turk Chess Player is one of the biggest hoaxes of the late 18th century. Built by Wolfgang von Kempelen, it was a wonder, a mechanical torso moving chess pieces to play a game against humans. In practice, it was driven by a small chess player hidden under the chessboard, who would see magnets showing the position of the pieces, and move with a pantograph the mannequin’s arm to reply to moves.
Chapter 38 - Lords of the Labyrinth
[24] Arthur Wesley – or Wellesley, as he’ll rename himself to bring back the old traditional family name – is better known in history as the Duke of Wellington. In this history, he’ll have gotten the title in a slightly different way, since the original version was in honour of defeating Napoleon. Do not worry, he will still prosecute the war against Bonaparte with great vigour, until the end!
