It means the Government pays almost two percentage points more than the German government.
Michael Wickens, of Cardiff Business School, said the threat of a higher-borrowing Labour Government is shaking markets.
“The higher UK yields since February is mainly due to UK political risk arising from the additional threats to the level of debt in the economy arising from an even more Left-wing and economically illiterate leadership,” he said in response to the survey.
“Arguably, yields before February should also have reflected the risk present since Labour entered government in July 2025. Higher UK inflation due to domestic energy policy has also raised yields.”
Lukasz Rachel, at University College London, said political events have been important drivers of higher borrowing costs.
“Gilts have moved on specific political news: by-elections, local elections, Burnham,” he said.
While the US also suffers from political uncertainty, its safe-haven status for global investors appears to protect the market, he added.
At the same time, weak demand for Britain’s long-term debt, combined with the Bank of England’s decision to sell bonds bought under quantitative easing, also pushed up borrowing costs, the economist said.
Higher borrowing costs on the nearly £3tn national debt represent another threat to Rachel Reeves’s plans for the public finances.
In March, on forecasts drawn up before the war in the Middle East had begun, the Office for Budget Responsibility forecast that the Chancellor would spend more than £109bn on central government debt interest this financial year, rising to more than £130bn per year at the end of the decade.