Explain the Marxist concepts in North and South, giving examples of how the working class is shown in the book.

Although Elizabeth Gaskell's novel North and South explores many of the issues of the plight of the new urban working classes in England's great manufacturing towns, the most immediate influence on Gaskell's work was not Marx per se.

First, as the wife of a Unitarian minister, William Gaskell, she lived in Manchester and had considerable first-hand knowledge of the poor families of the city. In 1837, some 11 years before the first publication of Marx's Communist Manifesto in German, Gaskell and her husband co-authored and published in Blackwood's Magazine a poem cycle about the poor of Manchester titled Sketches among the Poor. 

The second major influence on the novel was Charles Dickens. North and South was originally published in 20 weekly installments in 1854 and 1855 in a magazine named Household Words edited by Charles Dickens. Also serialized in the same numbers of the magazine was Dickens' novel Hard Times, which also concerned the plight of workers in England's new industrial towns. 

A third influence was Friedrich Engels who, like Marx, was a German philosopher who lived in Manchester, England and who later collaborated with Marx. Engel's 1845 volume, The Condition of the Working Class in England, influenced Marx, Gaskell, and many other thinkers, providing close observation and analysis of the inhumane working conditions in the great manufacturing towns of England. 

Marxist analysis enables us to read Gaskell in terms of theories of class conflict and of how religion and ideology play a part in the oppression of the working classes, although Gaskell herself was a devout Unitarian, and saw religion more positively than many modern Marxist theorists.

The most important characters in the book for our understanding of the working class are Bessie Higgins and her father Nicholas Higgins. Bessie Higgins is an example of how the inhumane conditions of the factories, in which the capitalists exploit the proletariat, lead to tragic consequences. She is dying due to the effects of toxic (air quality) working conditions and finds some solace in religion. While Margaret sees the importance of religion in providing comfort to the oppressed, she also argues:

Loyalty and obedience to wisdom and justice are fine; but it is still finer to defy arbitrary power, unjustly and cruelly used--not on behalf of ourselves, but on behalf of others more helpless.

This defiance is manifested in Nicholas, who sees the solution to capitalist oppression as unionization, which exemplifies the solidarity of the working class in resisting capitalist oppression, something Marx advocated.

A second major Marxist theme we find in the book is the notion that intellectuals are natural allies of the workers. Once Margaret abandons her initial false ideology she undergoes a transformation in consciousness that allows her to discover her purpose in the class struggle. This is symbolized by her setting aside many of her prejudices against the rough manners of the northerners and beginning to see their honesty and harshness, as opposed to the refined manners she learned from her mother, as grounded in a life of authenticity.