UK 30-Year Borrowing Costs Hit Highest Level Since 1998 as Iran War and Election Nerves Drive Gilt Selloff

The yield on 30-year UK government bonds climbed to about 5.78% on Tuesday, reaching its highest level since 1998 and marking a 28-year peak, as global energy-price fears collided with domestic political uncertainty ahead of local elections.

The Details

The 30-year gilt yield rose to roughly 5.78%–5.80% during trading on Tuesday, according to matched reporting from multiple outlets. The 10-year gilt yield also moved higher, reaching approximately 5.09%–5.12%, its highest level in about 18 years. Bond-market data snapshots vary slightly by outlet because they captured different moments during the session, but the directional move was consistent across sources.

Traders and analysts attribute the selloff in part to rising inflation fears following the escalation of the Iran war, which has disrupted energy markets and pushed oil and liquefied natural gas prices higher, especially around the Strait of Hormuz. The Strait of Hormuz is a critical chokepoint for global energy shipments, and any disruption there reverberates quickly through commodity markets and into broader inflation expectations.

The market pressure has sharpened the fiscal challenge facing Chancellor Rachel Reeves. Higher gilt yields increase the government's debt-interest costs and reduce her room to meet existing fiscal rules without further spending cuts or tax increases. Every basis-point increase in long-term borrowing costs translates directly into larger interest payments on the UK's stock of outstanding debt, tightening the fiscal envelope at a moment when Reeves is already constrained by her self-imposed fiscal targets.

Bank of England Governor Andrew Bailey, in remarks reported by the BBC, downplayed the idea of a uniquely UK-specific gilt crisis. "If you look at day to day... what's moving the market - in this respect, it's all to do with the conflict… also because what gets said about the conflict," Bailey said. His comments suggest that the central bank views the recent bond-market turbulence as driven primarily by external geopolitical factors rather than by a deterioration in UK-specific fundamentals.

At the same time, market participants say UK yields have risen more sharply than those of peer economies because global inflation pressure is intersecting with domestic political uncertainty ahead of local elections and broader leadership speculation around Prime Minister Keir Starmer. That combination has created a feedback loop in which international and domestic risk premia are reinforcing each other.

Luke Hickmore, bond director at Aberdeen Investments, told The Guardian: "Politics is not background noise. In today's gilt market, it is a fundamental part of the investment signal." His observation underscores that investors are watching the UK political calendar and leadership dynamics closely, treating them not as peripheral considerations but as core inputs into pricing decisions.

Context

The bond-market repricing comes after UK government borrowing for the full year to March had fallen to £132 billion, a three-year low. That improvement in the fiscal position has since been challenged by the escalation of the Iran conflict and the associated energy-market disruption. A lower headline borrowing figure earlier in the year had given Reeves some breathing room; the repricing of long-term yields has narrowed that margin considerably.

The Bank of England held interest rates at 3.75% last week but warned that inflation could come in higher than expected if the energy shock persists. The Monetary Policy Committee's decision to keep rates unchanged reflected its assessment that the underlying inflation trajectory remained uncertain, with the conflict adding a new layer of upside risk.

While the 30-year gilt yield has less direct impact on UK mortgage pricing than shorter-dated maturities, it serves as a key indicator of long-run government financing costs and broader fiscal credibility. Investors compare long-term yields across advanced economies, and a sustained spike in the 30-year gilt relative to equivalents in the United States, Germany, or France can signal concern about a country's debt-sustainability path.

What's Next

The trajectory of UK gilt yields will depend on developments in the Iran conflict and any corresponding moves in global energy prices, as well as the outcome of upcoming local elections and the direction of Bank of England monetary policy. The Bank of England's next rate decision and its updated inflation forecasts will be watched closely for signals on how policymakers are weighing the energy shock against domestic demand conditions. Investors will also be tracking any fiscal policy announcements from the Treasury.