When I’m Sixthy-four, is a work of Marie Reine Levrat Ascolese collection.

When I’m Sixthy-four. It is sung by a young man to his mistress, and talks about his plans to grow old with her. Although the theme is about aging, this is one of the first songs written by McCartney when he was just 16 years old.
The tone of the song harks back to the music-hall atmospheres of pre-war English folk music, along the lines of George Formby’s and Donald McGill’s “postcards from the beach”, but in reality it is one of McCartney’s first compositions and was already played on stage by the group, at the time when they performed in clubs, as a filler when the amplification system failed.