The Wolves of Willoughby Chase

Even the wolves are not as cruel as Slighcarp and Grimshaw

The action of this book takes place in a period of English history that never happened - shortly after the accession to the throne of Good King James III in 1832. At this time, the Channel Tunnel from Dover to Calais having been recently completed, a great many wolves, driven by severe winters, had migrated through the tunnel from Europe and Russia to The British Isles.

—Joan Aiken

The first written in a series of eccentric gothic adventure stories for children by Joan Aiken. The series is generally referred to by the same name (that or the 'Wolves Chronicles').

The twelve books feature a changing line-up of main protagonists, the most frequently recurring being cockney urchin Action Girl, Dido Twite, who have adventures in an Alternate History of the nineteenth century. Often the villains are Hanovarian conspirators, desperate to replace the incumbent James III with George Of Hanover. Other common threads are the motif of the wolves, the presence of awful nineteenth-century working conditions and a certain English barminess about the plots.

The books are part parody of, and part homage to, Victorian literature. They are a little like a prototype A Series of Unfortunate Events and in turn in is likely they are part of the very canon Daniel Handler was parodying and paying homage to with that series. Philip Pullman is also a fan and the influence of Dido Twite is clear in his own urchin Action Girl, Lyra Silvertongue.

The Wolves Chronicles (in narrative order):

The Whispering Mountain (1968) a prequel to the series
The Wolves of Willoughby Chase (1963)
Black Hearts in Battersea (1964)
Nightbirds on Nantucket (1966)
The Stolen Lake (1981)
Dangerous Games, published in the UK as Limbo Lodge (1999)
The Cuckoo Tree (1971)
Dido and Pa (1986)
Is Underground (British title: Is) (1992)
Cold Shoulder Road (1995)
Midwinter Nightingale (2003)
The Witch of Clatteringshaws (2005)

Tropes used in The Wolves of Willoughby Chase include:

Abusive Parents: Dido's parents are neglectful of her to the point of cruelty and her father in particular does not hesitate to imprison and endanger his daughter in the name of Hanovarian conspiracies. Much worse off though is another daughter, Is, who is used by her mother as a drudge and treated with nothing but casual violence and verbal abuse by her mother and father. It's never acknowledged outright by the pair that she is their child, probably since she is the product of an extramarital affair, a fact which might explain their disregard. An example of an abusive guardian is Miss. Slighcarp, to Bonnie and Sylvia in 'The Wolves Of Willoughby Chase, and to Dido and Dutiful Penitence in 'Nightbirds On Nantucket'.
Action Girl: Oooh yes. Pretty much any adolescent female character, even if they start out meek, and most adult female characters as well. Of particular note is Dido Twite, hero of seven of the books, and her half-sister Is, who follows her lead.
Adults Are Useless: Even the more helpful and benevolent adult characters tend to be some way off the quick wits of the child/teenaged heroes.
Affectionate Parody: Aiken is harking back to Victorian literature - mostly Dickens and childrens' writers like Frances Hodgson Burnett. Large parts of 'Nightbirds On Nantucket' are essentially a madder version of Moby Dick (Captain Casket is chasing a pink whale). Its hard to tell how straight the books are meant to be read by certainly the plots at some points are so eccentric as to be more parody than homage (did I mention about the pink whale? The characters befriend her by throwing her hard-boiled eggs from the beach).
- In turn they are almost certainly one of the series that influenced A Series of Unfortunate Events.
Anachronism Stew: See the page quote.
Apathetic Citizens: Justified in that the terrible things taking place in the books - forced child labor; horribly dangerous factories and mines etc - are barely exaggerated dangers of real nineteenth-century life, and realistically only a few people are interested in, or capable of, taking a stand against them.
Badass Bookworm: Owen in 'The Whispering Mountain'.
Bittersweet Ending: On occasion, for example in 'Is Underground', Is only succeeds in finding one of the missing boys she set out to alive, and her grandfather dies as well.
Bizarrchitecture: The London residence of the Duke Of Battersea. After years in the building, he commented it looked like a giant pink blamange and, irritated, died.
Card-Carrying Villain: Most of the series' antagonists, especially Miss Slighcarp of 'The Wolves Of Willoughby Chase' and 'Nightbirds On Nantucket'.
Chekhov MIA: In 'Black Hearts In Battersea', Simon is expecting to meet Dr. Field, who seems to have disappeared...
Cinderella Circumstances: About once a book in some form. Whether its because of an Orphanage of Fear or an evil governess, or simply circumstance, expect the characters to be forced into dreadful hard work and poverty at some point in the plot.
Competence Zone: Almost all the child or adolescent characters are sure to be quick-witted and ready to see through Hanovarian plots, with adults much less inclined to be much use. Some books even formalize this to some extent - in 'Dido And Pa' the urchins of London form a network called 'the birthday club' which is instrumental in the protagonists' victory. In 'Is Underground', the child mine-workers form a telepathic bond together which saves the day. In both cases there are only a few adult characters open and clever enough to be members.
Consummate Liar: Dido's pretty circumspect, and is able to dissemble and lie without much trouble or guilt.
Crapsack World: Most of the locations are pretty awful, particularly for children, but the children seem to regard their surroundings quite cheerfully on the whole. Dido pines for stinking, dangerous London even when in the relative idyll of Nantucket.
Cut Short: See Author Existence Failure
Deserted Island: In 'Black Hearts In Battersea'.
Devil in Plain Sight: Miss. Slighcarp.
Evil Teacher: Miss. Slighcarp again - though of course she was never a real teacher.
Have a Gay Old Time: The meanings of nineteenth-century slang has shifted somewhat. When the stories are in London, the characters frequently eat 'faggots', and when introduced Is is most frequently referred to as 'the Slut' meaning, in this case, drudge or maid-of-all-work.
Historical Artistic Licence
Honor Before Reason: Is Twite seems to have a particularly acute sense of duty, traveling to the horribly dangerous town of Blastburn/Holdernesse because she promised a dying uncle she barely knew she would find a cousin she doesn't know either. This is commented upon by several characters.
Idiosyncratic Episode Naming: For the First three books anyway.
Ironic Nursery Tune: The chapters of 'Is Underground' are headed with lines from nursery rhymes which emphasize how much of a Crapsack World Blastburn is compared to the 'Playland' the children were promised.
Istanbul (Not Constantinople)
Literary Allusion Title: It's possible Aiken was invoking Dido And Aeneas with the title 'Dido And Pa'.
Little Miss Badass: Most any adolescent female character the series features - but particularly Dido.
Loads and Loads of Characters
Luke, I Am Your Father: Simon and Sophie turn out to be the long-lost relatives of the Duke of Battersea, and Simon his heir.
Meaningful Name: A lot of Dickens-style naming: Slighcarp, Grimshaw etc. Bonnie is bonny. The surname Twite belongs to two characters (Dido and Is) often described in bird-like terms, and their father is a songwriter. Is's name connects her, in-universe, to a drowned town of the same name which becomes relevant by the climax of 'Is Underground'...
Named After Somebody Famous: ...Meanwhile, Dido's namesake doesn't seem at all relevant to her. In-universe she is named after a canal boat.
Never Was This Universe: The setting is more Alternate History than Alternate Universe, but the occasional supernatural elements like telepathy and werewolves veer towards this trope.
Orphan's Ordeal
Parental Abandonment: Either the protagonists are orphaned (Simon, Sylvia etc), believe themselves to be (Bonnie etc), have neglectful parents (Dido, Is etc), or their parents are removed from the action in some way (Dutiful Penitence).
Precision F-Strike: Rather surprising for a series usually filed in the 9-12 age range, the word 'bastard' is used as an insult on at least one occasion.
Punny Name: In universe, Is. It's mentioned to be the name of a legendary drowned town (which becomes relevant to Is Twite come the end of her eponymous story). The villain of the same story also threatens to turn her from 'Is' into 'Was'.
Raised by Wolves: In 'Black Hearts In Battersea', Sophie mentions having been raised by otters for a time.
Reasonable Authority Figure: Good King Jim is an all round good egg; kind and down to earth.
Shown Their Work: She might play fast and loose with history, but Joan Aiken clearly knew her stuff regarding nineteenth-century England and even details you might assume are flights of fancy can turn out to be based on fact. An evident interest in nineteenth-century nursery rhymes and playground games on the part of the author often comes to the fore.
Social Services Does Not Exist: no one's looking out for these urchins.
Steampunk: Sort of. There are enough anachronisms to the nineteenth-century settings to invoke this - see the page quote.
Sweet Polly Oliver: Bonnie from 'Willoughby Chase', and later Dido occasionally fits this trope - the latter does not really actively disguise herself as a boy but since she wears her hair short and wears trousers instead of skirts, she is often mistaken for a boy, and notes that this sometimes comes in useful. Furthermore, Sophie often disguises herself as her brother Simon once he is the Duke of Battersea and there are conflicting demands on his time. In 'Limbo Lodge' (known in the US as 'Dangerous Games'), Dido realizes early on that Doctor Talisman is in fact female.
What Happened to the Mouse?: The fact of shifting protagonists and a large cast means threads are often left open-ended. Before writing 'Nightbirds On Nantucket', Joan Aiken was inundated with letters from fans with this reaction regarding Dido Twite, who is last seen in 'Black Hearts In Battersea' clinging to driftwood in the middle of a stormy sea before disappearing and being presumed dead.