Referendums on electoral systems are relatively rare. In most countries changes to the electoral system are enacted through the legislatures. The British referendum in May 2011 is thus one of the rare examples. In this article it is shown that the apparently idiosyncratic factors in the referendum were consistent with general trends identified in other referendums. While the media focused on the harshness of the campaign, the referendum also resulted in surprising coalitions between long-term foes, thus suggesting that the referendum contributed to cross-party cooperation rarely seen in a majoritarian system like that of Great Britain.