The song was about Brian's mom's bird named Bijou.
One day, Freddie came over with Delilah to have an afternoon milkshake with Mrs. May. While stirring in the chocolate, somehow Delilah opened the bird cage and all hell broke loose. We all know that Freddie isn't too athletic, but Brian's Mom is very hard to knock down. Unfortunately, seconds before tackling Delilah, Bijou became a mid-day snack.
Thus, the song is really about Delilah AND Bijou. And that's why they're back-to-back on the album.
It's clear in the lyrics:
[i]You and me [/i](Delilah & Bijou[i]) we are destined you'll agree
To spend the rest of our lives with each other.
[/i]
Micrówave