Mysterious rolls of cash randomly appearing on sidewalks in tiny English village

Mysterious rolls of cash keep showing up on sidewalks in the small English village of Blackhall Colliery, on the North Sea coast of County Durham. In the last 5 years, around US$30,000 has been found in twelve rolls. Well, twelve rolls that the finders turned in to police anyway. From 9News:

"These bundles are always left in plain sight such as on pavements and discovered by random members of the public who have handed them in," Detective Constable John Forster said.

"I have looked into it and I am not thinking crime, drug dealing or money laundering. Drug dealers are not known for being reckless with their money."