If I stumble on an old coin or bill in a drawer, my first instinct might be to clean it up or rush to sell it, but those snap decisions can quietly erase hundreds or even thousands of dollars in value ...

Depending on how old or rare a coin is, it could sell for hundreds or even thousands of pounds. Article continues below ...

The coin will go on sale at an auction in London next week ...

An expert has urged people to check old coin tins for rare pennies worth thousands of pounds ...