D. G. Paz's Dickens and Barnaby Rudge (2006) makes for interesting reading if you're an English professor. Paz, a historian, is interested in one of the allegorical readings of Barnaby Rudge: that the novel, the bulk of which occurs during the Gordon Riots (1780), is actually about the Chartist movement. In contrast, Paz argues that the novel is most likely about what it says that it's about, and that we ought to pay attention to the original preface, which makes it very clear that the contemporary parallel Dickens has in mind is Victorian anti-Catholic agitation (97). How does Paz go about dismantling the argument in favor of the Chartist allegory?
1) Paz discusses everything involving the novel's writing, publication, and reception, including the time-table on which Dickens wrote it, the reviews, the opinions Dickens expressed about Chartism at the time (or didn't, of which more below), and the political history of Chartism itself during the relevant years.
2) He also lays out his objections to historicist readings of the novel on historical terms. For example, he points out where literary critics make basic factual errors, improperly use evidence dating after 1841 to explicate Dickens' attitudes before and during 1841, or manipulate documents to alter their meanings. His own evidence derives from unpublished as well as published sources; it does not depend entirely on pre-existing secondary sources (although, obviously, it builds on them).
3) He does not analyze the novel; his own argument is entirely context-driven.
Obviously, #3 provides the greatest shock to the literary critic's system, although Paz is hardly the only historian to write "around" literature in this fashion . While he isn't trying to lock down readings of the novel to only a single reading, as his use of scare quotations suggests--"What is Barnaby Rudge 'about,' then?" (159)--he does want to exclude the Chartist allegory on the basis of Victorian reception history. As Paz points out, neither anti-Chartists nor the Chartists themselves (118-19) thought that the novel had anything to do with Chartism. Just as importantly, he shows that Dickens himself doesn't appear to have cared all that much about Chartism at the time. Between Dickens and his contemporary readers, then, there's little evidence to support a twentieth- or twenty-first century reading that puts Chartism front and center.
Paz's approach doesn't do much (or anything) for anyone interested in Barnaby Rudge as, well, literature. However, as a historicist who keeps denying that she's a historian (to no avail, it seems), I found that the book had other things to say to me beyond its actual argument:
1) Once again, I'm reminded that those of us hanging out in English rarely "do" our own history; we usually rely on other people having done it for us. Elaine Freedgood notes this point in passing in The Ideas in Things: Fugitive Meaning in the Victorian Novel (2006), when she comments that her work "rel[ies] on mediations, those of historians of textiles and tobacco, of forestry and furniture" (5). I do think that it's easy to forget about the "lopsidedness" this induces, given that one can wind up with a revisionist literary history layered over an incredibly old-hat historical narrative. (Or, as Dad the Emeritus Historian-Graeco Roman Egypt observed, "We don't mind you using 'us'; it's just that you have a habit of using the wrong 'us.'")
2) Paz warns us off the assumption that authors will necessarily care about current events, political or otherwise.
3) In her review of the book, Carol Engelhardt Herringer comments that "[b]y contending that the context of a novel’s production must guide our reading of the novel, Paz also argues that literary works must be understood in their contemporary context, warning against modern critics who read into literature concerns that could not be discerned by the author or its first readers" . There's probably a case to be made that some concerns were so obvious that nobody thought it worth the while to mention them . Some audiences pointedly refuse to get "on message," as a resurrected Upton Sinclair might observe. And many critics would argue that they are analyzing a work's underlying assumptions, not projecting non-existent meanings "into" it. Still, one has to agree that if nobody noticed that a work's subversiveness--or, for that matter, its conservatism--at the time, then either it wasn't subversive/conservative or it was doing a really lousy job at same.
4) Again, though, this appeal to context fails once you're dealing with a work's formal and aesthetic qualities, since contemporary tastes don't necessarily shake out a century later.
One fascinating bit of trivia I garnered from Paz's book: I hadn't realized that when the novel was adapted for the stage, Barnaby was a breeches role (84-94).
 See, e.g., Sarah E. Gardner's Blood & Irony: Southern White Women's Narratives of the Civil War, 1861-1937 (2003), which does something quite similar (although Gardner is a little more attuned to genre than Paz).
 Carol Engelhardt Herringer, rev. of Catholic Sensationalism and Victorian Literature and Dickens and Barnaby Rudge: Anti-Catholicism and Chartism, Victorian Studies 50.3 (2008): 501.
 At NAVSA, the theatre historian Tracy Davis made a similar point about performance conventions ("Sonic Repertoire," 15 Nov. 2008).