The UK’s unwritten constitution: There are no real rules

Mark Leftly | 23rd June 2026 | Comment

The timing and in what circumstances a leader should stay or go are in flux, argues Mark Leftly.

Sir Keir Starmer is the 43^rd longest serving prime minister in our country’s history. If a brave enough soul challenges Andy Burnham to become the next Labour leader, Sir Keir could still leapfrog The Earl of Aberdeen – a mid-19^th century, landowning Peelite – into 42^nd place.

Assuming a coronation or the very possible failure of another candidate to get the support of the 81 MPs needed to stand, however, Sir Keir will stay 43^rd. He will have been in Downing Street for just two years and a few days in change. That’s one place and a few months ahead of Sir Anthony Eden, whose premiership was considered extremely short when he quit on grounds of ill health in 1957, shortly after the Suez crisis.

We’ve only had 58 prime ministers, yet five of the past six rank well outside the top 30 for length of time in office. Even David Cameron, who now appears to be a beacon of longevity at a little more than six years, fails to crack the top 20.

There is little doubt that each of those failures of durability can be explained by the unique circumstances of the time. This is also, however, a clear pattern that cannot be ignored by either politicians plotting their routes to the top or a public affairs industry that relies on a degree of stability to co-ordinate campaigns.

“Political gravity, accepting conventions and the inevitability of quitting under pressure are concepts rather than …

Subscribe to The Mace

Join the member community shaping British politics and stay ahead of what's really happening in the world of politics and public affairs, with expert analysis, breaking news, and insider insights from Westminster and Brussels. The Mace is the leading news source and resource for the government affairs industry, offering required reading and lobby intelligence for professionals.

To see what you are missing out on by not subscribing to The Mace, click here to download our full membership info-pack. This includes having no paywall on op-ed content or profiles/interviews, allowing professional profiles to be read with maximum impact and visibility by government, special advisers, MPs, peers, civil servants, and policy and political decision-makers.

King Charles: The real ‘special ingredient’ in our relationship with the USA

Lucy Carrier-Pilkington | April 29, 2026

King Charles’s address to Congress was designed to steady a strained special relationship. Twelve standing ovations later, the Palace had given Downing Street something politics could not: a

Did a “boys club” culture of Downing Street lead to the appointment of Peter Mandelson ?

Mace | April 29, 2026

Keir Starmer's "boys club" culture was called out during the grilling of Morgan McSweeney.

The Silent Engine: Why we must stop kicking the Civil Service and learn to love our Civil Servants

Neil Woollard | April 28, 2026

As the Charity for Civil Servants marks its 140th anniversary, Neil Woollard argues that the officials who keep Britain functioning are too often caricatured, underpaid and overlooked —

UK’s economic stability starts at sea, says the CEO of the Chamber of Shipping

Mace | April 28, 2026

Shipping moves 95 per cent of the UK’s trade. Most of the time, this happens smoothly until there is a global crisis, writes Rhett Hatcher, CEO of the

Modern history shows the Open University is key to rehabilitating extremists — so why are we making cuts to prison education?

Lucy Carrier-Pilkington | April 28, 2026

Amid cuts to prison education hours in England, Lucy Carrier-Pilkington looks back at the historic success of the Open University in Northern Ireland and why it is still