I haven't read The Professor, but Shirley is probably Charlotte Bronte's most political novel.
The novel, set at the beginning of the 19th century, focuses on Luddite attacks. The industrialist is represented by Robert Moore, who is initially determined not to give in at any cost and doesn't care what happens to his former workers after they're fired. The working class are generally seen as a group, especially the Luddites, but there's 1 individual- William Farren, a good, honest man put out of work. The author's views are clear. She disapproves of the Luddites' violent acts and portrays the leader of the 1st attack, Barraclough, as a drunken man, but at the same time sympathises with workers such as William Farren, and understands their anger. She sympathises with Robert Moore and sees the need of industrialisation, modernisation and technology development, but also makes him soften, repent his harsh attitude and find another job for Farren.
Her attitude is seen more clearly with the aid of some other characters. Mr Yorke, for instance, can be extreme and intolerant in his politics (interesting detail: he chooses to speak Yorkshire dialect though he can speak standard English and French), and bigoted in some matters, but after all he's good-natured, proud to those above him and kind to those below him, having sympathises with and always helping the working class. Shirley, 1 of the wealthy ones in the novel, helps others with her money. In short, Charlotte Bronte shows us the working class in their difficult times, their unemployment and poverty and suffering, their anger and desperation and thoughtless violent acts. The solution she offers, it seems, is that each person has to work, live a good, useful, honest life, and those more able should give a hand to help those less fortunate- Shirley does charities, Mr Helstone donates his own money to the church, Miss Ainley lives like a saint and places others' needs above her own, Mr Yorke helps the poor, etc. Apparently, it's easier to write about Luddites than about Chartists, while I would prefer to know her view on Chartists and their demands.
The other political aspect, as one may expect, is about women. It's characteristic of Bronte. She rants about the limitation of choice for women, exemplified by the case of Mrs Pryor, who only has the choice between marriage and a governess's life, and suffers from both, until she works for Shirley. Charlotte Bronte depicts sexists, such as Joe Scott, or milder, Mr Helstone and Martin Yorke. She creates conformist female characters, such as Misses Sympson and Misses Nunnely, who think that what's strange must be wrong, what's unusual must be improper.
Then she makes her characters speak. Caroline and Shirley discuss women's lives and job opportunities. Mrs Pryor speaks about her suffering as a governess and as a wife and tells Caroline that life is an illusion. The spinsters talk about their experience and unhappy unmarried life. Caroline dwells on the grief and solitary life of Mrs Pryor and her lack of choice, and the smallness of a woman's life. Rose Yorke rants about the "long, slow death" of all the women around her and yearns for something greater, fuller, more exciting out there. Mrs Yorke, a cynic, rants about the difficulties of being a mother and bringing up a bunch of children, and scolds Caroline for being a sentimentalist who knows nothing about the world. Caroline, who is generally timid, has an outburst before Mrs Yorke, which shows that, timid as she is, she has a strong will and a voice to defend herself. Shirley rants about men's misconceptions of women and misrepresentations of women in literature. Shirley ridicules Joe Scott for his sexism. Etc, etc.
In all of these cases, we feel that it's also the author speaking, not only the characters.
Then Mrs Yorke is silenced. Joe Scott is ridiculed. Martin Yorke yields. Mr Helstone the sexist sees Shirley as an exception, and follows her in her project. Mr Yorke, in a discussion on politics with Shirley, cannot respond to her arguments. Her characters win, she wins.
I can't help thinking of Virginia Woolf, who writes that Charlotte Bronte "had more genius in her than Jane Austen; but if one reads them over and marks that jerk in them, that indignation, one sees that she will never get her genius expressed whole and entire. Her books will be deformed and twisted. She will write in a rage where she should write calmly. She will write foolishly where she should write wisely. She will write of herself where she should write of her characters. She is at war with her lot. How could she help but die young, cramped and thwarted?"
In short, from the aesthetic point of view, she puts all of her private feelings into this novel and lets them distort her art.
From the political point of view, here she addresses the women's condition question further in Shirley than in other novels. In Jane Eyre and Villette, she mostly focuses on the life of a single person, here she elevates it, expands it, universalises it. Here, choosing the 3rd person's point of view, she explores the feelings of many girls and women, and writes about the smallness of a woman's life, the lack of opportunities, the limited choice, the suffering in the life of a governess or a wife when she has the misfortune of living with an unkind family or a bad husband, the solitary life of governesses and spinsters, the burden of a mother of many children, etc. In Jane Eyre, she, through Jane Eyre, argues that women have as much feeling as men; in Shirley, she indirectly argues that women have as much sense, as Shirley takes part in business and talks about politics just as men do.
Shirley is, in my opinion, 1 of her weaker works, but it's interesting, and different. Here is a political novel by an author associated with Gothic novels and romance and bildungsroman. Here is something different.