Before the 2008 financial crash, the average cash ISA rate was 5.5 per cent; rates slumped as interest rates were slashed and have remained at record-low levels since. Last year, the average one-year cash Isa rate was just 1.6 per cent.

Interest rate predictions have again been revised in recent weeks, with this year’s first rise estimated to arrive in August next year at the earliest. Last year, it was generally expected that rates would rise this year.

“Even the punchiest of predictions emerging from economists at the Bank of England have placed the base rate at 1.5 per cent in 2020,” said Chris Williams, head of Wealth Horizon.

“The MPC (Monetary Policy Committee) is in no rush to raise rates and even when it does, it is unlikely that this increase will be passed on directly by banks and building societies.

Williams urged savers not to be seduced by artificially high introductory rates, which he feels are generally a transitory marketing ploy that “vanish after a few months.”

“People should never assume that the price they get when they open the account is what they will have for the lifetime of the Isa.”