The UK national debt stands at a staggering £2.72 trillion, with annual interest payments of £71.06 billion.

That means the average interest rate on the debt is ~2.61%.

Given the Debt/GDP ratio of 126.41% and an interest rate of 2.61%, this debt is growing organically by 3.30% each year.

For all of 2024, the UK economy grew 0.8%.

Is the UK's debt sustainable?

I'll let you be the judge of that.

https://www.ons.gov.uk/economy/grossdomesticproductgdp/bulletins/gdpmonthlyestimateuk/december2024#:~:text=Looking%20at%20annual%20growth%2C%20output,by%200.4%25%20in%20same%20period.