Although be aware that depending on the wealth and location of your ancestor they may not appear on the register.
The legal requirement for voting registers (or poll books) to be kept was established under the reform act of 1832. Although in many counties and boroughs, poll books were kept centuries before.
Britain did not have universal male suffrage (the right for all men over 21 to vote without any qualifications) until 1918.
Before this men could only vote if they were a
householder, so younger sons over 21 could not vote if they still lived at home.
As of 1867 men had the right to vote in the
boroughs (urban areas) if they owned or lodged in property worth at least £10 a year. In 1884 this right was extended to men living in the
counties (rural) areas aswell, before 1884 men in the counties had ther right to vote but the qualifications were stricter and not the same as those for men in the boroughs. Before the 1832 reform Act the qualifications for having the right to varied greatly from place to place and the 1884 Act established a uniform set of qualifications for the towns and countryside.
For more info see wikipedia's entries on the many Representation of the People Acts for 1832, 1867, 1884, 1918, etc etc
http://en.wikipedia.org/wiki/Representation_of_the_People_ActSo don't be too disappointed if you can't find your ancestor on an electoral register!
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