Police had issued a warning over fake versions of the new £5 notes - despite claims it was impossible to copy.
Officers issued the alert after what appeared to be counterfeits of the new design were seized in Wadebridge, Cornwall.
Local police published two key differences between a real £5 note and a fake one.
The Big Ben clock tower appears in gold on the real note but the landmark did not appear at all on the ‘fake’.
Also, clear holograms appear on the top and bottom on the front of the new note while the ones discovered in Cornwall are coloured and not holographic.
But The Bank of England subsequently issued a statement saying the ‘fake’ fivers highlighted by police were genuine notes - but badly worn through ‘extreme use’.
A spokesman said: “Polymer notes are stronger than paper notes and last longer in usual day-to-day use but they are not indestructible.
“The Bank of England is aware that a small number of polymer £5 notes have been damaged due to extreme use, for example prolonged washing at high temperatures.
“In some cases this has resulted in the foil Elizabeth Tower (Big Ben) being removed.
“These notes are damaged genuine banknotes not counterfeits, and a lot of other security features remain intact such as the Queen’s portrait in the window and the microlettering.
“The Bank has not seen any counterfeit Churchill £5 notes printed on polymer.”