in olden days—(formal) in former times; in times long past (also: in days of old):
- In olden days audiences took the equivalentof a cut lunch to the theater and expected to be entertained for hour after hour.
in the old days—long ago; years ago:
- We descended the hill, and, passing by the waterhead his father so loved in the old days of his carriage tours, we drove to the church.