Yields on 20-year and 30-year UK government bonds surged to their highest since 1998 on Tuesday, as a rebellion by more than 70 Labour lawmakers threatened to topple Prime Minister Keir Starmer. The market rout reflects a growing political risk premium on British assets, with analysts at Citi warning that a leadership challenge could push 10-year borrowing costs above 5.25%. Starmer told his cabinet he will not resign.
The sell-off hit the long end of the curve hardest. By late morning in London, the yield on the benchmark 10-year gilt had climbed 10 basis points to around 5.101%, according to CNBC. The 20-year and 30-year yields also jumped 10 basis points each, touching levels unseen in nearly three decades.
The political trigger was immediate. Labour suffered heavy losses in last week's local council elections. The result does not alter the parliamentary balance.
It did, however, open a floodgate of internal dissent. More than 70 Labour MPs called for Starmer to step aside, arguing the vote was a direct public rebuke of his policy agenda. Starmer's response was swift.
During a routine cabinet meeting on Tuesday morning, he told ministers he would not resign, The Guardian reported. Work and Pensions Minister Pat McFadden emerged to tell Reuters that no one in the room had challenged the prime minister's leadership. "The country expects us to get on with governing," McFadden said. "That is what I am doing and what we must do as a cabinet."
But the numbers tell a precarious story. Under Labour Party rules, a formal leadership challenge requires the backing of 20% of the party's MPs. That threshold currently stands at 81 lawmakers.
The 70-plus who have already called for his head are dangerously close to that line. Starmer is the UK's sixth prime minister in a decade. His recent predecessors, Boris Johnson and Theresa May, both resigned under parliamentary pressure.
May stepped down within weeks of a poor local election showing in 2019. Jordan Rochester, head of FICC strategy for EMEA at Mizuho Bank, drew that exact parallel in a note to clients. "This looks more like the Theresa May example," he wrote, as reported by CNBC. "For many the writing is on the wall at this stage, it's just a matter of how quickly the exit happens." Rochester added that Starmer could yet survive into 2027, noting that Boris Johnson clung to power far longer than many expected. The bond market is not waiting to find out.
Matthew Ryan, head of market strategy at Ebury, said the verdict from traders "isn't pretty." "The bond vigilantes are out in full force," he said. "Investors are attaching a distinct political risk premium to UK assets, fearful of both a change in the status quo and a surge in gilt issuance under a more left-leaning prime minister."
That fear has a specific shape. The names circulating as potential successors include Health Minister Wes Streeting, former Deputy Prime Minister Angela Rayner, and Greater Manchester Mayor Andy Burnham. Rayner and Burnham are widely seen as more left-leaning than Starmer.
Burnham faces an additional hurdle: he currently lacks a seat in parliament and cannot become prime minister unless that changes. Strategists at Citi laid out the financial stakes in a note on Monday evening. Removing Starmer, they warned, could trigger "a leftwards shift in Labour policies and more expansionary fiscal policy." The result, in their view, would be "higher Gilt yields and a weaker GBP." They added that current yields do not fully price in an immediate leadership challenge.
A credible contest could push 10-year yields to between 5% and 5.25% or higher, and hurt domestic-focused FTSE 250 companies while potentially benefiting internationally exposed FTSE 100 constituents. The economic backdrop makes the political drama more volatile. Growth and living standards have stagnated.
The UK has faced a prolonged cost-of-living crisis after the Covid-19 pandemic and the Russia-Ukraine conflict. Public anger at the slow pace of economic reform has been growing. Last week's local elections saw significant gains for both the right-wing Reform UK and the left-wing Green Party.
Voters on both flanks punished Labour's perceived timidity. This is not the first time bond markets have reacted sharply to the political fortunes of Starmer and his Chancellor, Rachel Reeves. Last July, gilt yields surged after Reeves was seen crying in parliament amid reports her position was in jeopardy.
The government had just reversed her proposed welfare cuts following a rebellion from Labour politicians. The message from the bond market then was clear: political stability, or at least policy continuity, mattered more than the personalities involved. The same dynamic is playing out now, but with higher stakes.
Mohamed El-Erian, chief economic advisor at Allianz and a professor at The Wharton School, told CNBC on Monday that investors outside the UK should "keep an eye" on the situation. "If the prime minister goes and the chancellor goes, UK yields will spike, and that may have a bit of a spillover," he said. What this actually means for your family. Higher gilt yields translate directly into higher borrowing costs for the British government.
That feeds into mortgage rates, business loans, and the price of servicing the national debt. A sustained sell-off would squeeze an already strained public budget. The policy says one thing.
The reality says another. The government's fiscal room for maneuver shrinks with every basis point. Why It Matters: A leadership challenge against Starmer would be the first successful internal party coup against a sitting Labour prime minister since the party's modern rules were established.
The bond market reaction signals that investors view a leftward policy shift as a material risk to UK fiscal stability. For ordinary Britons, the turmoil could mean higher mortgage payments, tighter credit, and less government spending on public services at a time when the cost-of-living crisis has already eroded household budgets. - More than 70 Labour MPs have called for Keir Starmer to resign, putting him within striking distance of the 81 votes needed to trigger a formal leadership challenge. - UK 20-year and 30-year gilt yields hit their highest levels since 1998, with analysts warning 10-year yields could breach 5.25% if a credible challenge materializes. - Potential successors including Angela Rayner and Andy Burnham are seen as more left-leaning, fueling market fears of higher government borrowing and a weaker pound. - The political crisis compounds an already fragile economic backdrop of stagnant growth and a prolonged cost-of-living squeeze. The immediate trigger for a challenge is the 81-MP threshold.
Starmer's opponents need to convert roughly ten more lawmakers to their cause. The coming days will reveal whether the rebellion has that momentum. If it does, the party must navigate a leadership contest while in government—a process with no recent precedent in Labour history.
Beyond Westminster, the market reaction will be the real-time arbiter. Every spike in yields tightens the fiscal noose. The Bank of England, which has been battling inflation with higher interest rates, will watch the political risk premium closely.
A disorderly sell-off could complicate its policy path. Both sides claim victory. Here are the numbers.
The 10-year yield at 5.101% is a verdict, not a prediction. The bond vigilantes have cast their vote.
Key Takeaways
— - More than 70 Labour MPs have called for Keir Starmer to resign, putting him within striking distance of the 81 votes needed to trigger a formal leadership challenge.
— - UK 20-year and 30-year gilt yields hit their highest levels since 1998, with analysts warning 10-year yields could breach 5.25% if a credible challenge materializes.
— - Potential successors including Angela Rayner and Andy Burnham are seen as more left-leaning, fueling market fears of higher government borrowing and a weaker pound.
— - The political crisis compounds an already fragile economic backdrop of stagnant growth and a prolonged cost-of-living squeeze.
Source: CNBC
