UK bond yields have surged to their highest levels in 28 years, driven by a confluence of political instability and global economic shocks that are reshaping investor confidence in Britain’s fiscal credibility. The 10-year gilt yield breached the 5% threshold on Tuesday, a level not seen since 1998, while the 30-year bond yield touched 5.81% – a 28-year high – before edging back slightly as Sir Keir Starmer fought off an immediate leadership challenge.
This morning, the yield on 30-year UK government bonds dropped by 4.4 basis points to 5.72%, and the benchmark 10-year yield fell 4 basis points to 5.06%. The moves are relatively small, but they signal that some calm is returning after a day of extreme volatility. Investors appear relieved that Health Secretary Wes Streeting did not launch a formal challenge, though Starmer remains under intense pressure after more than 70 Labour MPs publicly called for his resignation following heavy losses in last week’s local elections. The King’s Speech, scheduled for today, is expected to provide a temporary reprieve by focusing attention on the government’s legislative agenda rather than its internal divisions.
Bond market reaction: a repricing of risk
The sharp rise in UK borrowing costs is not simply a short-term panic. Analysts describe it as a “structural repricing of fiscal credibility”, reflecting deeper fears about the direction of policy under any future government – whether a more left-wing Labour leader or a Reform UK administration led by Nigel Farage.
Ipek Ozkardeskaya, senior analyst at Swissquote, said: “Brits are grappling with their own political shakeups after Nigel Farage scored big in the latest elections. The name Farage resonates in markets as a clearer path toward looser fiscal policy, higher spending and larger deficits, just as investors are already worried about Britain’s debt and inflation outlook. That combination is pushing investors to demand higher compensation to hold UK government debt, sending the UK 10-year gilt yield back above 5%. The higher the borrowing costs, the less the government can borrow, and the impact on growth would be negative.”
Market strategist Bill Blain of Wind Shift Capital questioned whether Reform UK could be seen as a safe pair of hands by bond markets. “Who in Reform is going to run the bond market / spending plan optimisation game?” he wrote. “Reform has clear intent to govern. Over the next three years – how will they persuade the bond market they can?”
Lloyd Harris, head of fixed income at Premier Miton Investors, argued that the upheaval over Starmer’s leadership reveals a fundamental issue: government credibility. “The Labour Party is not driven by one individual. It is shaped by its internal dynamics and by its union base, both of which tend to favour a more expansive fiscal stance. Markets understand this. They do not price the best-case scenario, they price the probability weighted outcome. Where fiscal discipline risks giving way to political pressure, yields adjust accordingly.” He pointed to recent remarks by Greater Manchester Mayor Andy Burnham – who said the UK has to “get beyond this thing of being in hock to the bond markets” – as a trigger for the sell-off. “Bond markets do not need to be challenged; they need to be convinced.”
Former hedge fund manager Rich McDonald, speaking on LBC’s Tonight with Andrew Marr, warned that a prolonged leadership contest would be damaging. “If we saw, let’s say Andy Burnham decided to run and there was some talk of a move to the left and more spending, I don’t think that would be taken well. And therefore, the bond market would give out a warning. If we see yields go anywhere near 6%, that’s going to really scare people and it’s going to put up the cost of spending that we already have on our large debt position.” He described Tuesday’s jump in 30-year yields to 5.8% as “awful”, adding that the long gilts “have a very strong message for Labour: get your house in order.”
Political turmoil and investor confidence
The crisis gripping Labour goes beyond a single leadership question. Nigel Farage’s Reform UK party performed strongly in traditional Labour and Conservative heartlands in the local elections, with Farage hailing the results as a “historic shift in British politics”. The party’s platform, often associated with looser fiscal policy and increased spending, is another factor pushing up yields. Investors are pricing in scenarios where either a Labour leader backed by the party’s union base or a Farage-led government pursues expansionary budgets that could swell the deficit and stoke inflation.
Goldman Sachs economist James Moberly noted in a research note that “the bulk of the selloff” in UK government bonds since the Iran war began is due to investors repricing the outlook for UK interest rates, rather than political risks alone. But he acknowledged that any future policy choices will “remain constrained by the challenging backdrop of rising spending pressures and an already elevated tax burden.” Moberly’s team estimated that higher gilt yields and lower growth might reduce the government’s fiscal headroom by around £12bn (0.3% of GDP). Much of that is attributable to the Iran war and the resulting energy shock, which has pushed up borrowing costs for many governments, not just the UK.
Morgan Stanley economist Bruna Skarica put the hit to headroom from the Middle East-related forecast revision at £11bn, though she noted that debt servicing costs pose an upside risk. At her last budget, Chancellor Rachel Reeves doubled her “headroom”, or buffer, against her fiscal rules to £22bn. The jump in energy prices since the Iran war began is driving up inflation, leading to higher borrowing costs when the government sells debt to bond investors. It also fuels the cost of living crisis, leaving households with less money to spend, hurting growth.
Despite the political noise, Goldman Sachs argued that there are “no immediate implications from higher political risk” for the Bank of England’s Monetary Policy Committee. While a more expansionary fiscal policy under a new Labour leadership could eventually boost demand and inflation, the bank’s analysis does not suggest the MPC has historically responded to signs of political risk by raising rates. Moberly expects the Bank to leave interest rates on hold this year, though if energy price pressures keep building it could raise borrowing costs this summer.
City firm TS Lombard described the UK as “the harbinger of things to come” in a new note, pointing out that Britain has suffered under the new “macro supercycle” – which includes a multipolar global order, increased conflict, and more interventionist national policies. The firm argued that the UK has “frontrun all the downsides of the new macro regime and none of the upsides”, with little hope of catching the upsides any time soon. It forecast that political volatility will continue to reign in the next few months, though risks of a blowout budget seem overdone, and the UK is closest to the brink of recession if the Middle East shock rolls on.
Farmers and oil markets under pressure
The economic fallout from the Iran war is striking far beyond the bond market. UK wheat farmers are facing potential losses of £70,000 on their 2027 crop, according to new analysis from the Central Association for Agricultural Valuers (CAAV). Jeremy Moody, the CAAV’s secretary, described the crisis in the Gulf as the “fifth hammer blow to arable economics after the last three problematic harvests and the present one”, moving into territory where “the combination of strained cash flow and credit with current prospects opens up the prospects of a significant fall in cereals planting this autumn.” His analysis shows that losses from crops now outweigh any additional income the average farmer would get from environmental schemes or farm diversification. Farmers are also battling extreme weather, uncertainty over the government’s EU reset, and the proposed Carbon Border Adjustment Mechanism, which is expected to add to the cost of imported fertilisers.
Meanwhile, global oil inventories are being drawn down at a record pace. The International Energy Agency (IEA) reported that global oil inventories fell by 129 million barrels in March and a further 117 million barrels in April, as countries dipped into their reserves to cover the shortfall following the Middle East conflict. The IEA, which ordered the largest release of government oil reserves in its history in mid-March, said: “More than ten weeks after the war in the Middle East began, mounting supply losses from the Strait of Hormuz are depleting global oil inventories at a record pace.” The agency forecasts that world oil demand will contract by 420,000 barrels per day this year to 104m bpd, which is 1.3m bpd fewer than it expected before the Iran war began. “The petrochemical and aviation sectors are currently most affected, but higher prices, a weaker economic environment and demand-saving measures will increasingly impact fuel use,” it added.
The jump in energy prices is also eroding the UK’s fiscal headroom. Morgan Stanley’s Skarica noted that higher debt servicing costs reflect what the Bank of England and the gilt market see as “limited spare capacity to absorb additional material fiscal demand.” She added that “political choices remain the key risk for 2027, where we think the skew is towards a wider deficit than our already above-OBR forecast.” The National Institute of Economic and Social Research (Niesr) has warned of a £35bn economic hit and a risk of recession this year due to the war.
Despite the turmoil, the UK stock market opened higher on Wednesday, with the blue-chip FTSE 100 up 66 points (0.65%) to 10,331, boosted by mining stocks following a rise in the copper price. The more domestically focused FTSE 250 rose 0.4%. Average two-year fixed mortgage rates dipped slightly to 5.74% from 5.75%, while five-year rates held at 5.67%, according to Moneyfacts. Later today, the Bank of England’s Catherine L Mann is due to deliver a speech on “The UK’s international exposures and vulnerabilities”, a topic that has rarely felt more pertinent.
