Parliamentary Voting System and Constituencies Act 2011

The Parliamentary Voting System and Constituencies Act 2011 (c. 1) is an act of the Parliament of the United Kingdom that made provision for the holding of a referendum on whether to introduce the Alternative Vote system in all future general elections to the UK Parliament and also made provision on the number and size of parliamentary constituencies.

Source: Wikipedia — Parliamentary Voting System and Constituencies Act 2011 (CC BY-SA 4.0)