The electoral register is updated every year, it lists the people in each property, on each street who can vote. It can help you find out how long your ancestor stayed at an address and early electoral registers tell you what your ancestor's job was.
Electoral registers will not list all the adults who lived in a property until 1928. This is because the electoral register only lists people who could vote. Before 1918, only men who were homeowners could vote. In 1918 the law changed so all men over 21 could vote but all women over the age of 21 weren't able to vote until 1928.