During his time in Manchester, Engels took notes and personally observed the horrible working conditions of English workers. These notes and observations, along with his experience of working in his father's commercial firm, formed the basis of his first book The Condition of the Working Class in England in 1844. Engels was only twenty-four year old when he wrote the book.
For twenty months he went about the part of the town that nobody from his class ever visited. Engels wrote that during his stay in England he purposefully forsook the company and dinner parties, the portwine and champagne of the middle-classes. He devoted his time interacting with the working classes in their everyday life.

In addition to his personal experience, he gained insights into the city through literary authorities as well as official records, parliamentary commissions, factory inspectors’ reports, newspapers and official statistics.