(a) The existence of a large urban population means that there would be greater number of individuals in need of a place to stay. This increased demand for places of residence is profitable for private landlords who can then rent out rooms at high rates. In nineteenth-century London, individual landowners made huge profits by taking advantage of the helplessness of the hoards of migrants in the city who needed a place to live.
(b) The existence of a large urban population means that there are increased cases of crimes, social conflict and rebellion. Police are responsible for maintaining the law and order. Hence, a police superintendent would definitely have increased work on his/her hands. In nineteenth-century London, policemen had a tough time controlling crime during the migrant influx. In the 1870s, there were 20,000 criminals living in London. The job of a policeman was made more complex in hunting down pick-pockets, thieves, cheats and tricksters whose numbers kept multiplying.
(c) The existence of a large urban population implies the simultaneous presence of several social problems, such as problems of housing, food, water, etc. These issues become policial issues when they are taken up by political parties. A political party and its leaders can mobilise the masses to support them in these political causes. This was the case in nineteenth-century London as well.