No they haven't. They decided they don't want ranked choice voting (known in the UK as the 'alternative vote'). Proportional representation is a different system, which the minority Liberal Democrat party and others had long argued for and quite a lot of people regarded the substitution as a form of bait-and-switch. Additionally some had reservations about the scheduling of the referendum to overlap with local elections in parts of the UK.

https://en.wikipedia.org/wiki/2011_United_Kingdom_Alternativ...