Finders Keepers, Losers Weepers

A woman has been convicted of theft for finding a twenty pound note in a shop and keeping it. She has been fined and now has a criminal record. Was she right? The Theft Act 1968 says: 
"A person is guilty of theft if he dishonestly appropriates property belonging to another with the intention of permanently depriving the other of it...

"A person's appropriation of property belonging to another is not to be regarded as dishonest… if he appropriates the property in the belief that the person to whom the property belongs cannot be discovered by taking reasonable steps."

Because she made no effort to trace its owner, she was deemed a thief. 
We humans may not know the moral laws but we are still guilty of breaking them. Thank God the Saviour's blood wipes the guilt of all our sin- known and unknown, commission and omission.