This is a straightforward song about a time honoured British tradition. After Christmas, big stores - in the capital and other major cities - discount their leftover stocks heavily, and housewives especially join the rush. People have been known to camp out waiting for them to open, literally, sometimes for days.
The sheet music, copyright 1966, is included in Songs of The Singing Postman Allan Smethurst Souvenir Album, which was published by Dick James Music the same year.
Suggestion credit: Alexander Baron - London, England, for above 2