The Lascelles Principles are a constitutional convention in the United Kingdom beginning in 1950, under which the sovereign can refuse a request from the prime minister to dissolve Parliament if three conditions are met:
The convention was in abeyance from 2011 to 2022, when the sovereign's prerogative power to dissolve Parliament was removed by the Fixed-term Parliaments Act 2011. Following passage of the Dissolution and Calling of Parliament Act 2022, which repealed the Fixed-term Parliaments Act, these principles are thought to have been revived.[1]
The Lascelles principles are not the only convention governing how the sovereign makes decisions relating to changes of government. For example, the Cabinet Manual notes the historic precedent of the sovereign dismissing a government under reserve powers. However, this was last done by William IV, who dismissed Lord Melbourne’s government despite majority support in the Commons and is thought to have damaged the sovereign’s reputation.[2]
The general principles of government formation also affect this decision. The Cabinet Manual stresses that the monarch should not be exposed to political decisions and "it remains a matter for the Prime Minister, as the Sovereign's principal adviser, to judge the appropriate time at which to resign".[2] The Manual notes that recent Prime Ministers have chosen not to resign until an established situation was set which the sovereign could be advised to accept.[2]