The excesses and scandals of the Boris Johnson era have fuelled demands for new constitutional rules to limit and constrain the executive, and particularly the prime minister. However, anyone hoping to find here the distinctive blend of historical insight, witty phrases and nostalgic respect for past political and civil service leaders that is typical of Peter Hennessy’s writing may be disappointed. There are just a few Hennessy touches – including in the title – and occasional appeals to the wisdom of the good and the great. This is essentially the work of Andrew Blick, a former pupil of Hennessy and now a professor at King’s College London and an authority on the constitution.

Blick is more of the Gradgrind school and, alas, a frequent user of that evasive academic cliché ‘problematic’. He assembles the case for the prosecution against the former prime minister in a comprehensive way, assessing his conduct against the yardsticks of the Ministerial Code, the Cabinet Manual and the Nolan principles of public life, as set out by Lord Nolan in 1995. No one disputes that Johnson has always been a rule breaker in every aspect of his life. By the summer of 2022, as William Hague wrote at the time, Johnson had displayed ‘disloyalty … to the conventions of government and institutions of government and to the massed ranks of colleagues who did their best to support him but ultimately quit in disgust or told him to go’. These powerful points are worth making afresh in view of the evidence that a sizeable number of Conservative party members and MPs regret his departure and hanker after his return. The Jacobite flame still burns.

Yet was the bending of constitutional rules and conventions – the bypassing of parliamentary scrutiny and established rules and conventions – just a reflection of the personal flaws of one prime minister? Blick and Hennessy convincingly argue that the events of recent years have exposed deeper and longer-standing flaws