Case study Party-gate. A constitutional Crisis

Lord (Peter)Hennessy argues that the convention of Individual Ministerial responsibility has been broken by the PM as he misinformed parliament about knowledge of parties attended during lockdown.

Hennessey describes the ‘good chap theory of government’.

Whereas every other Western democracy has codified its system of government, Britain’s constitution is a mish-mash of laws and conventions, customs and courtesies. Britain sees no need for the legalistic writing down its constitution in one place. Instead it relies on the notion that its politicians know where the unwritten lines of the constitution lie, and do not cross them.

“The British constitution is a state of mind,” says Peter Hennessy, a historian who calls this the “good chap” theory of government. “It requires a sense of restraint all round to make it work.” Yet amid Britain’s current crisis, such restraint has been lacking.

As he put it in 2019, “We have long assumed that those who rise to high office will be ‘good chaps,’” who understand the rules and choose to observe them. That has left us vulnerable to those who are not “good chaps,” but are willing to smash those rules for their own advantage.


The norms and conventions of the UK’s uncodified constitution are being pushed to their limits – and sometimes beyond. In the absence of clear legal rules, the constitution relies on a shared understanding of what constitutes good behaviour in public and political life, and trust that people in positions of power will abide by that understanding. The constitutional historian Peter Hennessy describes as this as the “good chaps” theory of UK government.