Kids in Treasure Hunt

[Purukivel]

Howdy, back again with a question I've culled from somebody else's query on another site:

"I need help trying to find the title of a movie british? in the 60's? or 70's?
Synopsis: A group of children in search of a treasure hidden near an old water mill. By opening the trunk, we realized that it did not contain a true treasure, but chocolate coins!

This is not Treasure at the Mill (1957) by Max Anderson."

[Corinne]

Sounds like my kind of treasure.