The electoral system had remained the same since it was put in place by the 1832 Reform Act.
But it came under increasing pressure throughout the 1840s and 50s from the reformist movements. By the mid-1860s, Parliament was in the process of extending the vote to the working class.
In 1866, all voters had to be male adults over 21 years of age. The right to vote was still based upon a property qualification.
By the early 1860s around 1.43 million could vote out of a total population of 30 million.
In 1867, the Conservative government introduced the Parliamentary Reform Act. This increased the electorate to almost 2.5 million.
The most important change was the granting of the vote to occupiers in the boroughs (people who rented properties rather than owning them) and as a result the electorate in some of the newer towns in England and Scotland increased dramatically.
However, the Act did not alter the balance of political power in Britain. The middle classes still dominated the electorate in both towns and boroughs.