Decoding Labour's manifestos from Blair to Starmer: Radicalism and issue trends

The recent general election in the United Kingdom (UK) resulted in a landslide victory for the Labour Party under the leadership of Keir Starmer. Labour secured a parliamentary majority with 412 seats compared to the Conservative Party's 121 seats, marking Labour's second-largest majority since 1997 and the Tories' worst result in their history.

In preparation for a Labour government, Penta published its "A House United" report on Labour's prospective parliamentary candidates' views and political priorities to help members of the business community understand the Party's policy direction. But now that the election is over, analysts are seeking to understand which factors drove Labour's huge victory, as well as what Labour will practically do with its sizable majority.

It was widely acknowledged that discontent with 14 years of Conservative rule and the UK's sluggish economic growth meant that this election was Labour's to lose. Others have argued that Labour's cautious approach to making electoral commitments helped ensure their victory. Penta set out to investigate the relationship between Labour's political positioning and their electoral performance by analyzing the key campaign material that the Party releases before every general election: the party manifesto.

Penta's project

We analyzed five Labour Party manifestos to answer the following questions:

1. How has the relative "radicalism" of the Labour Party's platform changed under different party leaders?
2. The manifesto is just one element of an election that reflects the external social and political context and does not alone explain Labour's performance, but is there a correlation between each manifesto's "radicalism" and each respective leader's electoral success or failure?
3. How has the salience of different policy issues (e.g., cost of living, immigration, climate, etc.) changed in party manifestos over time?

Specifically, Penta conducted a text analysis of the most significant manifesto published by each of the last five Labour leaders: Tony Blair (1997), Gordon Brown (2010), Ed Miliband (2015), Jeremy Corbyn (2019), and Starmer (2024). We analyzed mentions of key terms for different issues that have been top of mind for UK voters, examining how the discussion of issues has evolved over time and determining the relative radicalism of each manifesto via a human text-analysis based score and an LLM-generated score.

1. Candidates running on more moderate manifestos won more parliamentary seats than their more radical peers

Our analysis determined that Starmer's manifesto is the most moderate since Blair's in 1997. As expected, Corbyn's 2019 manifesto was significantly more radical than those of his peers. Across the board, Labour leaders running on relatively moderate manifestos won more parliamentary seats than those who campaigned on more radical platforms; Blair and Starmer won the largest number of parliamentary seats in two landslide victories, while Corbyn won the fewest seats of the peer group. These correlations are not necessarily causal—many factors go into an electoral victory or defeat—but on the question of whether Starmer's platform is indeed the most moderate since that of Blair, our results are clear.

2. Key mentions related to migration, defense and foreign affairs, and the environment were fairly consistent over time, but Corbyn's manifesto was a notable outlier on climate

Exploring the content of party manifestos, mentions of terms related to migration, defense and foreign affairs, and the environment and climate in Labour manifestos remained fairly consistent between 1997 and 2024. One notable outlier is mentions of terms related to the environment and climate in Corbyn's second manifesto, which peaked at 131 in 2019. In particular, Corbyn used more progressive terms, such as "climate emergency," "climate justice," "environmental emergency," and "green transformation," none of which were used in his peers' manifestos.

One of Starmer's campaign pledges, meanwhile, is to set up Great British Energy—a publicly-owned energy company investing taxpayers' money into clean energy technology, projects, and infrastructure. The relative lack of environment and climate mentions in his manifesto seems to reveal a strategic communications decision to downplay the Party's progressive approach to climate action, particularly given voters' concerns about the financial cost of such action. This strategy may have been informed by last year's Uxbridge and South Ruislip by-election, where the expansion of a tax on polluting vehicles (Ultra Low Emission Zone (Ulez)) contributed to Labour's loss.

3. Manifestos reveal both change and continuity in Labour's priorities over time

Note: *Includes words such as "Devolution" and "Devolve"; **Includes words such as "LGBTQ" and "LGBTQ+"; ***Includes words such as "Racism" and "Racist"; ****Includes words such as "Palestine" and "Palestinian."

Analysis of hot-button terms further reveals the similarities and differences in Labour's priorities since 1997. Housing is a consistent feature of manifestos over time, as is the NHS, though the manifestos of Brown and Starmer stand out for their mentions of the UK's health service. The increasing prevalence of social issues can also be observed via manifestos—the terms "LGBTQ" and "Racism" first appeared in the manifestos of Miliband and Corbyn, respectively.

Starmer's manifesto is a reflection of the times: on foreign affairs, we saw more mentions of NATO and Palestine than any of his predecessors; on social issues, we observed a downplaying of human rights and LGBTQ+ issues relative to Corbyn's manifesto.

4. Jobs and costs were mentioned more frequently in Corbyn's and Starmer's manifestos than in those of their predecessors

An issue that has been top of mind for voters is the UK's cost-of-living crisis: food, energy, and heating prices have soared amidst the pandemic and the war in Ukraine. Labour under Starmer therefore made economic growth the centerpiece of its campaign. Starmer even listed "deliver economic stability" as the first of his six pledges, also known as his "First Steps for Change." Perhaps unsurprisingly, then, we found that mentions of "inflation" and "costs" were most frequent in Starmer's manifesto compared to those of his peers and that mentions of those two terms—along with "jobs," "wage," and "wages"—have generally increased between 1997 and 2024, demonstrating the increasing salience of the economy and cost of living as a campaign issue.

Conclusion

Labour's performances in general elections—its successes have, famously, been few and far between—are determined by factors beyond the Party's political positioning. But our analysis quantitatively demonstrates what we qualitatively know: in broad terms, more moderate Labour Party manifestos translate into more parliamentary seats.

It is therefore tempting to herald Labour's win as a triumph for centrist politics in the UK. However, Nigel Farage and his right-wing populist political party Reform UK—with its base spread thinly across the country—won five seats in the House of Commons with approximately 14% of the popular vote and finished second to Labour in more than 100 seats. On the left of the political spectrum, the Green Party made a breakthrough, winning four seats. There is clearly some space for radicalism in British politics, and this would be reflected in far more parliamentary seats if a proportional voting system was in place.

Nonetheless, it is often said that whichever of the two major UK political parties—Labour and the Conservatives—stands on the most moderate platform wins the general election. Our analysis suggests that, in 2024, that old adage proved correct once again.