Once in Manchester (1842), Engels did in fact to very well in business using his off time to pursue writing articles and reading books as well as reports on economic and political conditions. He took notes on child labor, the environment and the general life of the laborers which would provide the material and inspiration for The Condition of the Working Class.... He met with members of English labor and Chartist movements and the articles he was feverishly working on were published in The Northern Star, New Moral World and the Democratic Review. While in Manchester, Engels also met Mary Burns, an Irish working girl, and they cultivated a relationship not unlike a marriage (although Engels did not believe in the institution of marriage) that lasted until her death in 1862.
Engels decided to return to Germany in 1844, but on his way back to Barmen he met with Marx in Paris. The two had first met on Engels' way to Manchester in Cologne but at that point the two did not necessarily impress each other as they did when meeting again in France. Marx edited two of Engels' articles that laid out what would become a version of Engels ideas on scientific socialism for the Deutsch-Französische Jahrbucher. The principles in the papers outlined how private property was a major flaw in the liberal economic system. He also helpedKarl Marx with writing an attack on his earlier friends, the "Young Hegelians" which developed into the work The Holy Family. In Barmen, Engels published his notes he had gathered in Manchester and The Condition of the Working Class in England in 1844 was published in 1845.