Final answer:
Political cartoons were more effective in mid-19th century Britain due to an increase in public literacy from compulsory education and the expanded suffrage which made public opinion more influential in politics.
Step-by-step explanation:
A political cartoon in mid-19th century Britain would have been more effective during that time than in earlier periods for several reasons. The increase of suffrage among the populace, leading to a need for influencing public opinion, plays a key role. The introduction of compulsory public education in 1870 under the Elementary Education Act resulted in a more literate population capable of understanding and being influenced by political cartoons. Public education meant that a larger segment of society could interpret the nuances of a political cartoon, and the expansion of suffrage meant that their opinions mattered more in national affairs. Furthermore, cartoons could reach a broader audience due to technological advances such as widespread newspapers and public posters, making them a powerful tool for satire, political commentary, or indoctrination. With a public that was not only more educated but also had greater influence over national politics, the impact of a political cartoon was notably more significant.