my year 2 teacher taught us this song in 1973, perth australia.
i too decided to check internet as no one else seemed to know the song.
so glad i did.

mrs becks version

leetle mister baggy breeches
i love you
will you be my sunday fellow
i patch em with purple, mit pink and mit yellow
and folks will say, as we lean on the old sea wall
lena's been patching his jakops til he's got no breeches at all

ya ya ya patches big patches small
yaya ya he's got no breeches at all