Cash in a bank pays interest, usually moving with the Bank of England's base rate. That interest is the nominal return. Meanwhile inflation raises prices, so each pound buys a little less. What's left after inflation is your real return: roughly, the interest rate minus the inflation rate.
Cash doesn't fall in value the way shares and bonds can, and deposits are protected by the FSCS up to a limit per person per bank, so check the current figure. Its risk is slower and easier to miss: when inflation runs above the interest rate, the balance goes up while what it buys goes down. The Balance Sheet widget on your dashboard, set to Cash, shows how much of your money is in cash. It doesn't track interest paid — the Portfolio page only estimates a year's interest from a rate you type in — and the app doesn't adjust any returns for inflation.
Illustrative rates. The balance went up; what it buys went down.
Educational content only. It is not personal financial advice.