In the early days after the Referendum, Brexit seemed impossible to implement. Theresa May, despite her reputation as capable and highly organised, seemed to face one obstacle after another from Parliament and her Party. Boris Johnson, on the other hand, succeeded her with the promise of “getting Brexit done” and managed to do so. Five years after Brexit took place, Monika Brusenbauch Meislová and Birgit Bujard look back at what allowed Johnson to succeed where May failed.

With the publication of a number of books and studies on the premiership of Boris Johnson which take a critical perspective as to the effectiveness of his leadership it is easy to forget that there is at least one policy area in which Johnson was an effective political leader during certain parts of his premiership: the domestic politics of Brexit withdrawal and future UK-EU relationship negotiations.

While May faced continual setbacks in her attempts to pass a Brexit deal through Parliament, Johnson managed to lead the UK out of the EU.

Brexit has posed an immense challenge to several British prime ministers, forcing them to tackle profound political divisions inside their parties and the country as a whole, as well as complex negotiations with the EU at the same time. Theresa May and Boris Johnson, two Conservative prime ministers who succeeded each other, faced some similar challenges at the beginning of their premierships, such as no or only a slim majority in parliament, but their leadership delivered very different outcomes when it came to the domestic politics of Brexit. While May faced continual setbacks in her attempts to pass a Brexit deal through Parliament, Johnson managed to lead the UK out of the EU. What explains these distinct outcomes?

A good starting point to answer this question is Richard Heffernan’s “power resources” model to compare the political leadership of May and Johnson, focusing on how each employed two types of resources – personal and institutional – to navigate the domestic politics of Brexit between June 2016 (the period right after the EU referendum) and December 2020 (the conclusion of the EU-UK Trade and Cooperation Agreement). Doing this will help us understand how differently the two prime ministers approached their leadership and why Johnson ultimately succeeded where May did not.

What explains Theresa May’s and Boris Johnson’s divergent leadership outcomes in managing Brexit is their different level of ability to mobilise their personal and institutional resources.

Heffernan’s power resources model: a brief overview

According to Heffernan, prime ministers derive their power from two main sources: personal and institutional resources. Personal power resources relate to a leader’s skills, ability and reputation as well as the PM’s association with actual or anticipated political success, public popularity and high standing in their party. Institutional resources include the PM’s position as legal head of the government, the option to set the policy agenda, appointing the cabinet etc. Effective political leadership requires a prime minister to strategically mobilise both types of resources.

What explains Theresa May’s and Boris Johnson’s divergent leadership outcomes in managing Brexit is their different level of ability to mobilise these resources. In the period until the end of December 2020 Johnson was able to be predominant in his political leadership on the domestic politics of Brexit, something Theresa May never achieved.

May’s leadership style – characterised by caution, secrecy, and an over-reliance on a small circle of close advisors – quickly proved a liability.

Personal power resources

Theresa May began her premiership with a reputation of being capable, competent, and highly organised, having built up significant political capital during her time as Home Secretary. Initially, this made her seem to be a stabilising force amid the political turbulence following the EU referendum. However, May’s leadership style – characterised by caution, secrecy, and an over-reliance on a small circle of close advisors – quickly proved a liability. Her phrase “Brexit means Brexit” was meant to project decisiveness, but it was vague and failed to provide the clear direction her party and the public needed. This lack of clarity, combined with her isolated approach, limited her ability to gain the trust and support of a broader range of stakeholders. Furthermore, May’s political standing weakened significantly after her snap election gamble in 2017 backfired, leading to the loss of the Conservative Party’s parliamentary majority. This decision, intended to strengthen her mandate, instead left her reliant on the Democratic Unionist Party to govern. The failure to deliver a majority, combined with her inability to get the Withdrawal Agreement passed in  Parliament, severely damaged her credibility, and she was increasingly seen as a leader who was unable to fulfil her central mission.

Unlike May, Johnson used his media skills and public presence to keep his leadership in the domestic politics of Brexit strong.

In contrast, Boris Johnson possessed more personal power resources than May. Known for his charisma and ability to connect with various stakeholders, Johnson leveraged his populist style to rally support. His simple, bold messaging, epitomised by the “Get Brexit Done” slogan appealed to voters exhausted by years of political deadlock. Johnson’s reputation as a strong leader grew further after he renegotiated  elements of the Withdrawal Agreement, which was seen as a significant victory after May’s repeated failures. This success, combined with his victory in the 2019 general election, positioned Johnson as a leader with a potential to deliver on his promises. Unlike May, Johnson used his media skills and public presence to keep his leadership in the domestic politics of Brexit strong. His association with success – especially in terms of claiming to have renegotiated the Withdrawal Agreement, when it was in fact mainly the section on Northern Ireland, and in leading a party that had secured a decisive electoral victory – cemented his position as the prime minister capable of breaking the Brexit impasse.

May’s secretive approach to decision-making, which concentrated power among a small group of close aides, alienated broader circles within her party and contributed to her losing control over the institutional apparatus of government.

Institutional power resources

Theresa May struggled to fully utilise these resources. Her cabinet was divided, and her efforts to balance the conflicting viewpoints in it made it extremely difficult for her to build a united front. High-profile resignations, including that of Boris Johnson as Foreign Secretary and David Davis as Brexit Secretary over May’s plans on the future relationship with the EU, further weakened her leadership, signalling a loss of control over her own government. As May’s authority diminished, so did her ability to steer the Brexit process effectively. Additionally, her secretive approach to decision-making, which concentrated power among a small group of close aides, alienated broader circles within her party and contributed to her losing control over the institutional apparatus of government.

Boris Johnson, in contrast, made skilful use of the institutional power resources at his command. Upon taking office, Johnson reshuffled his cabinet, removing dissenters and replacing them with Brexiteers who supported his hardline approach. This move ensured that his government was united behind his Brexit stance and enabled him to centralise decision-making. By consolidating control over key governmental structures and ensuring his cabinet was aligned with his agenda, Johnson was able to effectively negotiate and pass his version of the Brexit deal through Parliament. Johnson also streamlined government operations to ensure tighter control over the Brexit process by No. 10, making sure that his vision for Brexit remained central to the process by delegating the responsibility to realize it to David Frost.

Theresa May’s and Boris Johnson’s varied use of personal and institutional power resources highlights the reasons for the different outcomes of their premierships in the context of Brexit. Johnson possessed more personal power resources and drew upon the available institutional power resources more effectively than May. As a result, unlike May, he was able to be predominant in the domestic politics of Brexit.

The above draws on the authors’ published work in British Politics: “Prime ministerial political leadership and the domestic politics of Brexit: Theresa May and Boris Johnson compared”

All articles posted on this blog give the views of the author(s), and not the position of LSE British Politics and Policy, nor of the London School of Economics and Political Science.

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