Why the Hormuz crisis is pushing UK borrowing costs to their highest since 1998

A geopolitical crisis unfolding in the Middle East is now sending shockwaves through Britain’s financial system, pushing government borrowing costs to levels not seen in nearly three decades.

At the heart of the turmoil lies the Strait of Hormuz, a narrow but crucial passage through which roughly 20 per cent of the world’s oil supply flows. Any disruption, real or anticipated, immediately rattles global energy markets. And that is precisely what is now unfolding.

Oil prices have surged amid fears of supply disruptions, and for an energy-import-dependent economy like the UK, the implications are swift and severe. Higher crude prices feed directly into fuel, transport, and manufacturing costs, ultimately pushing up headline inflation. For bond investors, that is a red flag.

UK gilt yields, effectively the interest rate the government pays to borrow, have spiked sharply, touching levels last seen in 1998. The surge reflects a fundamental repricing of inflation and interest rate expectations. Investors now believe that the Bank of England will be forced to maintain a tighter monetary stance for longer to contain inflationary pressures triggered by the energy shock.

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This “higher-for-longer” interest rate outlook is critical. When markets expect rates to stay elevated, existing bonds with lower yields become less attractive, pushing their prices down and yields up. As a result, the UK government must offer higher returns to attract buyers for new debt issuances.

The problem is compounded by Britain’s already fragile fiscal position. Public debt remains elevated, and higher borrowing costs significantly increase the government’s interest burden. Every uptick in gilt yields translates into billions of pounds in additional debt servicing costs over time.

At the same time, the growth outlook is deteriorating. Rising energy prices act as a tax on households and businesses, eroding disposable income and squeezing corporate margins. Consumer demand weakens, investment slows, and economic momentum falters. This creates a stagflationary environment, where inflation remains high but growth stagnates, a combination that is particularly damaging for bond markets.

There is also a structural vulnerability at play. Unlike major oil exporters, the UK cannot benefit from higher energy prices through export revenues. Instead, it faces a worsening trade balance and imported inflation. That asymmetry makes UK assets more sensitive to global commodity shocks.

Adding to the pressure is a broader shift in global capital flows. As geopolitical risks rise, investors are reassessing where to park their money. While UK gilts have traditionally been seen as safe assets, they are now competing with higher-yielding alternatives such as US Treasuries. To remain attractive, UK bonds must offer a higher risk premium.

The psychological factor cannot be ignored either. Markets are forward-looking, and even the perception of prolonged instability in the Hormuz corridor is enough to anchor higher inflation expectations. Once these expectations become embedded, central banks are forced into more aggressive policy responses, reinforcing the cycle of rising yields.

In effect, the Hormuz crisis has become a catalyst for a broader financial tightening in the UK. It has exposed the economy’s dependence on external energy supplies, amplified inflation risks, and intensified fiscal pressures, all at once.

The spike in borrowing costs to levels last seen in 1998 is not just a market anomaly. It is a signal that global geopolitics, energy security, and domestic economic fragilities are now deeply intertwined, and that even distant conflicts can have immediate and profound consequences for the UK’s financial stability.