The bank set more than 1,000 British adults a ten-question personal finance exam, similar to GCSE standard, with the number of adults not achieving a GCSE-level C grade or an O level pass numbering one in ten, the equivalent of 4.7 million Britons. Issues including credit card interest, negative equity and secured loans repayments were all tackled in the questions, which were taken from previous exam papers.

Abbey said that following the examinations, 25 per cent of those that undertook the tests scored the equivalent of an A*, whereas 30 per cent scored an A. When the 21 per cent that achieved a B level are added, some three-quarters are covered in the top three grades, but 24 per cent are not. "While most people are in the realms of a GCSE pass almost five million British adults would fail a simple personal finance exam," said Steve Shore, head of banking at Abbey. "Quite worrying given we selected questions that we felt everyone with a bank account should know."

Following the research, Abbey has also released a list of the top five questions that stumped those that took the tests. Some 86 per cent did not know that six weeks were allowed to pay back a balance on a credit card before interest is accrued, while just under half (47 per cent) were unaware what negative equity meant.

Almost a quarter (23 per cent) of those that took the Abbey exam did not know that non-payment of secured loans could lead to the house it is secured against being sold to cover the loan, while seven per cent thought that the contents of a house, rather than the house itself, would be sold to pay off the secured loan.

The Abbey research seems to support government plans to introduce a personal finance element into Maths GCSE and this is something that the bank itself is calling for. "Abbey certainly welcomes the government's plans to introduce a much-needed personal finance element into the curriculum. We would also urge anyone who doesn't understand something on their bank statement to contact their branch or a financial adviser," Mr Shore said.

Other issues that puzzled those that took the test concerned unpaid cheques and bank statements, as well as the meaning of hire purchase agreement, something that left more than one in ten (12 per cent) confused.

In July, the ifs School of Finance welcomed the decision by the Financial Services Authority (FSA) to call for mandatory teaching of financial education in schools across Britain. The organisation welcomed the "stronger place" financial education would fill in the curriculum after the FSA called on Ed Balls to work to achieve this. Along with the Abbey research, a study by Lloyds TSB last month showed that young people are concerned about taking on too much debt, suggesting that education about products such as personal loans and current accounts could prove beneficial for schoolchildren.