UK borrowing costs have spiked sharply amid a global bond market rout, with ten-year gilt yields jumping from 5.24 per cent to 5.35 per cent on Wednesday—the biggest one-day movement in three weeks—and rising further to over 5.38 per cent by Thursday. This surge affects not only government borrowing costs but also pushes up mortgage rates and business loan costs for households and companies. The timing is particularly awkward for Prime Minister Andy Burnham, who has defended previous remarks about Britain being overly dependent on bond markets, comments that have contributed to investor nerves about his government's spending plans, though global factors including rising US yields, oil prices and interest rate concerns also drive the sell-off.

Gilt yields have climbed to levels unseen since 2007, having sat below 5 per cent when Burnham took office. Average two-year fixed mortgage rates now stand at 5.92 per cent—the highest since July 2024—whilst five-year rates sit at 5.96 per cent, levels last seen in October 2023. The strain on government finances is evident, with debt interest payments hitting a record £8.8 billion in August, taking total interest payments on the near-£3 trillion national debt to £50 billion for the first five months of the fiscal year. Burnham has insisted his earlier comments about reducing dependence on bond markets were misrepresented and that he was advocating for a more "streamlined, productive state" rather than reckless spending.