What is the impact of referendums?

An element of direct democracy has been injected into a political system previously wedded to representative democracy.
However, the extent to which referendums have enhanced UK democracy is debatable. Referendums have extended political participation and made government more responsive to the people on major constitutional issues, but they have created competing legitimacies (e.g. should parliament or the people have the final say?) and some of the information presented by referendum campaign groups has been misleading.

The doctrine of parliamentary sovereignty is the cornerstone of the British constitution.
It states that parliament is the highest legal authority and can make law on any matter of its choosing.
The predominance of parliament is also central to representative democracy.
Citizens elect MPs to take decisions on their behalf: MPs are representatives who make up their own mind on issues rather than delegates who must follow instructions from voters.
The use of referendums on major constitutional issues marks a shift towards popular sovereignty in which the people, rather than parliament, take the ultimate decision.
This has created competing claims of legitimacy.
Most UK referendums are not legally binding, and parliament retains the authority to respond as it sees fit — though legislation meant the government would have been required to change the electoral system in the case of a ‘yes’ vote in the 2011 AV referendum.
A clash of competing claims of legitimacy was evident after the 2016 EU referendum.
It was followed by debate on whether and how the government should invoke Article 50 of the Lisbon Treaty in order to leave the EU.
Some people prioritised parliamentary sovereignty, arguing that the referendum had not authorised the terms of Brexit and that parliament must be asked to give its consent for the country to leave the EU but others warned that attempts to bypass or dilute the referendum result would damage the legitimacy of the government and political system.

Since the 1997 devolution referendums, it has become a constitutional convention that further changes to the devolved settlement would require approval in a referendum.
The Government of Wales Act 2005 permitted the Welsh Assembly to gain new powers if they were approved in a referendum — as happened in 2011.
The Scotland Act 2016 states that the Scottish Parliament and government cannot be abolished unless approved in a referendum in Scotland.