UK government borrowing costs are at their highest since the 2008 financial crisis, with the yield on ten-year gilts climbing above 5 per cent and threatening to squeeze the headroom available to Chancellor Rachel Reeves.
On Tuesday the ten-year yield reached 5.1 per cent, before easing to 5.06 per cent on Wednesday, according to market data. That compares with roughly 4.5 per cent for most of the early months of 2026 and 4.27 per cent before the outbreak of the conflict in the Middle East. The thirty-year gilt yield also rose sharply, hitting its highest level since 1998 on Tuesday, and was still above 5.7 per cent in early trading on Wednesday.
Why UK bond yields have risen more than other nations
While government bond yields have increased across most advanced economies since the start of the war in Iran, the UK has been hit hardest. Andrew Goodwin, chief UK economist at Oxford Economics, said: “The increase in UK government bond yields since the start of the Iran war has been greater than in most other advanced economies. Markets clearly perceive the UK has a bigger inflation problem and that tighter monetary policy will be needed to limit second-round effects from the energy shock, while political uncertainty has added to pressures at the long end.”
Oxford Economics’ data shows that UK ten-year government bonds have risen by more than 70 basis points since the conflict began, compared with around 40 to 45 basis points for Japan, Germany, the United States and France.
Several factors are driving the divergence. The war in Iran has disrupted oil and gas transportation and supply, pushing up energy prices. As a major energy importer, the UK is particularly exposed to the resulting inflationary shock. The Bank of England’s Monetary Policy Committee noted at its April 30 meeting, when it kept the benchmark interest rate at 3.75 per cent, that a larger or more protracted energy shock would require a more restrictive policy stance. Markets have since scaled back expectations of further rate cuts and now anticipate the Bank may have to raise rates again.
Domestic political uncertainty has compounded the pressure. Prime Minister Sir Keir Starmer’s leadership has been called into question after poor local election results on May 7, 2026. Analysts suggest the prospect of prolonged political turmoil or a leadership contest could lead to looser fiscal policy, straining public finances and causing investors to demand a higher risk premium on UK debt. Sterling weakened further after Sir Keir’s speech addressing Labour’s losses on May 11, and gilt yields surged to multi-decade highs the following day.
Structural changes in the pension sector are also weighing on gilt demand. Historically large buyers of gilts, pension funds are maturing and shifting their investment strategies, particularly for defined benefit schemes. The reduction in demand for long-dated gilts, combined with the high volume of new issuance and the Bank of England’s quantitative tightening programme, adds further upward pressure on yields. Mr Goodwin expects ten-year yields to remain at or above 5 per cent this year given this mix of inflationary pressures, fiscal uncertainty and changes in the pension market.
Pressure on public finances
Higher gilt yields directly translate into higher borrowing costs for the government, meaning more money must be spent on debt repayments and less is available for public services or industry support. The 20 basis-point jump in the ten-year yield since May 9 is estimated to add £2bn to the debt interest bill by the end of the decade, according to market calculations.
Oxford Economics calculates that the combination of rising bond yields, expectations of interest rate rises and other market conditions could reduce Chancellor Rachel Reeves’ fiscal headroom by £6bn, bringing it down to £17.6bn between now and the Budget later this year. However, the research suggests this should not alter fiscal policy directly, because Ms Reeves took what the report calls “the sensible decision to significantly increase her margin for error at the 2025 Budget”. She raised headroom against her fiscal rules to £22bn in November 2025, up from £9.9bn previously.
Matt Britzman, senior equity analyst at Hargreaves Lansdown, warned of the broader economic consequences. “It’s a tough mix: higher borrowing costs, weaker confidence and less room for the government to offer support if the economy slows,” he said. Oxford Economics projects the UK economy will expand by only 0.8 per cent this year, a significant downgrade from earlier forecasts, as the headwinds from higher energy costs, political uncertainty and tighter monetary policy take their toll.
