Finding a £20 note turned out to be very bad luck for one Stoke-on-Trent woman - it cost her £175.
Nicole Bailey, 23, picked up the cash from the floor of a local One Stop shop and slipped it into her pocket in a spirit of 'finders keepers'.
However, the money belonged to another customer, who had dropped it after withdrawing money from a cashpoint outside the store, and who had already reported the loss to staff.
As a regular customer, Ms Bailey was easily identified by staff when the store's CCTV was checked; and although she at first denied taking the money, she confessed after seeing the footage.
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Ms Bailey - who has no previous convictions - has now been convicted of theft and ordered to pay £175 in court costs and charges and given a six-month conditional discharge.
According to her solicitor, she'd assumed that there was nothing wrong with keeping the money herself - but legally, that isn't the case. By not handing it in, she was 'permanently depriving' the true owner, which amounts to theft.
"Morally, the right thing to do is hand in any found property so that the person who has lost out has every opportunity to be reunited with it. This was someone's hard-earned money and we are committed to supporting all victims in our community," says Chief Inspector Karen Stevenson, from Stoke South Local Policing Team.
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If you do find money, you should hand it in to the police - but there's still a chance you could get to keep it. If it's not claimed within 28 days, it's yours.
Most people wouldn't bother to do this with a small amount - although police say they do get sums as little as £5 handed in from time to time. But a survey a few years ago from Alliance & Leicester revealed that, even with as much as £100, more than half of people would simply keep the cash - potentially committing theft.
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The law does allow some leeway. You're only expected to take 'reasonable steps' to return the money to its rightful owner, and you certainly wouldn't be expected, say to hand in a pound coin that you found in the street.
But if it's a large amount, or if you know who the money belongs to, it's definitely theft. In the case of Ms Bailey, it made a big difference that the money was found in a shop rather than in the street, as this would have made it much easier to reunite the lost cash with its owner.