The novel is chiefly set in 1855.[1] The fictional historical background diverges from our timeline around 1824, at which point Charles Babbage completes his Difference Engine and proceeds to develop an Analytical Engine. He becomes politically powerful and at the 1830 general election successfully opposes the Tory Government of the Duke of Wellington. Although Wellington stages a coup d'état in 1830 in an attempt to overturn his defeat and prevent the acceleration of technological change and social upheaval, he is assassinated in 1831. The Industrial Radical Party, led by a Lord Byron who survives the Greek War of Independence, comes to power. The Tory Party and hereditary peerage are eclipsed, and British trade unions assist in the ascendancy of the Industrial Radical Party (much as they aided the Labour Party of Great Britain in the twentieth century in our own world). As a result, Luddite anti-technological working class revolutionaries are ruthlessly suppressed.
By 1855, the Babbage computers have become mass-produced and ubiquitous, and their use emulates the innovations that actually occurred during our information technology and Internet revolutions. Other steam-powered technologies have also developed and so, for example, Gurney steam carriages become increasingly common. The novel explores the social consequences of an information technology revolution in the nineteenth century, such as the emergence of "clackers" (a reference to hackers), technologically-proficient people, such as Théophile Gautier, who are skilled at programming the Engines through the use of punched cards.
In the novel, the British Empire is more powerful than in our reality because of the development and the use of extremely-advanced steam-driven technology in industry. In addition, similar military technology has enhanced the capabilities of the armed forces (airships, dreadnoughts, and artillery) and the Babbage computers themselves. Under the Industrial Radical Party, Britain shows the utmost respect for leading scientific and industrial figures such as Isambard Kingdom Brunel and Charles Darwin. Indeed, they are collectively called "savants" and often raised to the peerage on their merits, causing a break with the past as regards social prestige and class distinction. The new patterns are also reflected in the educational sphere: classical studies have lost importance to more practical concerns such as engineering and accountancy.
Britain, rather than the United States, opened Japan to Western trade, in part because the United States became fragmented by interference from a Britain that foresaw the implications of a unified United States on the world stage. Counterpart successor states to our world's United States include a (truncated) United States; the Confederate States of America; the Republic of Texas; the Republic of California; a communist Manhattan Island commune (with Karl Marx as a leading light); British North America (analogous to Canada, albeit slightly larger in this world); and Russian America (Alaska). Napoleon III's French Empire holds an entente with the British, and Napoleon is even married to a British woman.
In the world of The Difference Engine, France occupies Mexico, as it did briefly in reality during the American Civil War. Like Great Britain, it has its own analytical/difference engines (ordinateurs), especially used in the context of domestic surveillance within its police force and intelligence agencies. As for the other world powers, Germany remains fragmented, with no suggestion that Prussia will eventually form the core of a unified nation, as it did in our own timeline in 1871, which may be caused by French sabotage analogous to that pursued in the case of the fragmentation of the United States noted above. Japan is awakening after the British ended its isolation, and looks, as in our timeline, set to become one of this world's leading industrial and economic powers from the 20th century onward.
The intervention of Lords Byron and Babbage provide famine relief with grain confiscated from the landed aristocracy. The Great Famine of Ireland never occurred, there is no agitation for Irish home rule or Irish independence and the Irish instead have become enthusiastic supporters of the Radical regime. A Spanish Civil War is mentioned to be taking place in 1855 with one side being the Royalists, and in 1905, possibly as a result of that conflict, there is an independent Republic of Catalonia.
Among other historical characters, the novel features "Texian" President Sam Houston, as an exile after a political coup in Texas, a reference to Percy Bysshe Shelley (as a Luddite), John Keats as a kinotropist (an operator of mechanical pixellated screens), and Benjamin Disraeli as a publicist and tabloid writer.
