Britons are spending as much as £83 billion a year without knowing where the money went, according to research by Visa. A survey of over 1,000 people revealed that the average UK adult spends £33 every week with no recollection of what the money bought.

With that amount, Visa said, the average household could have paid for the following:

- everyday power and water bills for the whole year;

- 96 per cent of travelling costs for the year;

- all the weekly grocery shopping for three quarters of the year;

- 72 per cent of home improvements costs each year;

- three months' mortgage payments.

Monitoring money through online banking and keeping a record of what cash withdrawals are used for could provide much needed assistance.

So too could greater use of direct debits or separate bank accounts for bills or family holidays. But it appears the UK consumer is just not that organised.

The survey shows that the three occasions when people are most likely to mystery-spend are when they are shopping for food or other groceries (51 per cent); out and about with children or grandchildren (48 per cent) and on a night out (47 per cent).

Men are more likely to mystery-spend than women - averaging £36 a week versus 29. But women are twice as likely to forget what they spent after shopping with friends than men.

The survey also pointed to a degree of recklessness in youth, with 18- to 24-year-olds confessing to mystery spending £50 per week, closely followed by 25- to 34-year-olds who cannot account for £48 of their weekly spending. The best age category was the over 55s who put the rest of the nation to shame by losing track of just £15 per week. As 75 per cent of people make a habit of checking their bank or credit card statements, it is clearly just their cash spending that remains a mystery.

Eva Chapple, a mother of two from Lincoln, said that over the years she had learnt to keep a track on where the money was going.

"From my student days in London until our first child was born, I seemed to make endless trips to the cashpoint and not worry too much about where the money was spent - usually on a night out!"

Things changed when she started a family.

"When I took time off work to have kids, we were suddenly on one salary so we were forced to keep track of where the money was going," she said.

"We used direct debits as much as possible and tried to budget our use of cash a lot more. We also set up a separate joint account, which we pay into each month, to fund our summer holiday.

"Allocating money in this way makes it far easier to keep track of spending. Money is only used for what it is set aside for."

Anthony Grimes from Shrewsbury said online banking had made it much easier to see where his money was going.

"I think being able to check your bank balance 24 hours a day from home is a huge benefit and shows where your money has gone," he said.

"But it is where the cash withdrawals are spent that cause the confusion.

I tend to take out cash for specific things that I can budget for rather than just keep my wallet well stocked."