His latest report showed that will be easily managed this tax year, as the excess of income over expenditure will be £10.2bn and the accumulated surplus £52.7bn. Over the next five years that surplus will grow each year to reach £76.2bn by the end of 2026/27, when it will equal 55pc of the benefits paid out. The actuary works on the assumption the fund needs a surplus of just 16.7pc to manage the ups and downs of taxes in and benefits out. 

This year the actuary gave some figures for what he called the “hypothetical scenario” of applying the triple lock to state pensions this April. He found that would, of course, reduce the surplus. But there would still be a surplus balance of £56.3bn in 2022/23, and £50.8 billion in 2026/27, the furthest ahead he looks. Both are more than double the balance needed to operate the national insurance fund safely. 

The rise in NI contributions in April will not affect the surplus of the fund, as all the extra money raised is earmarked for the NHS and is taken out before the balance is paid into the fund for pensions and benefits. 

The balance and surpluses in the fund are used to offset part of the national debt, reducing the need for the Government to borrow and cutting the interest it pays. But that is small comfort to 12 million pensioners facing a real-terms cut in their pension for the first time in many years.

The Department for Work and Pensions told Telegraph Money: “The one-year move to temporarily suspend the triple lock ensures fairness for both pensioners and taxpayers. Combined with last year’s 2.5pc increase to pensions – a step we took when earnings fell and inflation barely rose – we have ensured pensioners’ incomes have been protected.” The Government actuary’s department declined to comment.

Paul Lewis is the presenter of BBC Radio 4’s Money Box