Chancellor Philip Hammond confirmed the the NS&I bond he announced at Autumn Statement will be available from April and will pay 2.2% on deposits up to £3,000.

However, Maike Currie, investment director for personal investing at Fidelity International, said: “Has Chancellor Hammond made an error in his infamous spreadsheet calculations for the NS&I Bond? A rate of 2.2% over a three-year term barely covers the OBR’s inflation expectations.

“While this may a market-leading rate, anyone saving into the new investment bond will struggle to achieve a real return with OBR expectations for inflation to rise to 2.4% in 2017, 2.3% in 2018, before falling back to 2.0% in 2019.

“To stand any chance of generating an inflation-beating return in the current environment, you’re far better off looking further up the risk spectrum, investing in bonds issued by companies rather than the Government or moving into stocks and shares.

“If anyone is unsure about the benefits of investing in the stock market over stashing cash under the mattress, our calculations show if you had invested £15,000 into the FTSE All Share index 20 years ago you would now be left with £53,974. If, however, you had invested £15,000 into the average UK savings account over the same period, you would be left with a paltry £19,877.That’s a difference of £34,097 – too big for any sensible saver to ignore.”