Britain’s fiscal watchdog warned that the country’s public finances are on an unsustainable path, with government debt forecast to soar from roughly 96% of gross domestic product to more than 270% by the early 2070s. In its annual Fiscal Risks and Sustainability report, the Office for Budget Responsibility said successive U-turns on tax and spending have left the UK in a “relatively vulnerable position” and reduced its capacity to cope with future shocks. A major pressure point is the state pension triple lock, which the watchdog calculates now costs about £15.5 billion a year—three times the figure assumed when the policy was introduced in 2012. If maintained, pension spending would rise to 7.5% of GDP within five decades. The OBR also cited the recent abandonment of planned welfare cuts, estimating that the move could add roughly £12 billion a year to expenditure and further narrow the Chancellor’s headroom against her fiscal rules. Investors have reacted nervously. Thirty-year gilt yields climbed to 5.45%, the highest level in a quarter-century, and the OBR projects Britain’s annual debt-interest bill could increase by £22 billion as pension schemes scale back purchases of government bonds. The combination of higher rates and heavier borrowing costs underscores the market’s sensitivity to fiscal slippage. Prime Minister Keir Starmer’s office said it is working to stabilise the public finances, but ministers have declined to rule out new revenue measures, including a wealth tax. Separately, calls are growing to lift the two-child benefit cap—a step the Children’s Commissioner estimates would lift 500,000 children out of poverty—adding further complexity to the budget calculus ahead of the Chancellor’s autumn statement.