Does anyone know anything about where the Copper Family song "When Spring Comes In" comes from? It's in their songbook, but they don't say much about it. Thanks for any help!

When spring comes in, the birds do sing,
The lambs do skip and the bells do ring,
While we enjoy their glorious charm,
So cheerful and so gay.

The primrose blooms and the cowslip, too.
The violets in their sweet retire,
The roses shining through the briar,
And the daffa-down-dillys which we admire
Will die and fade away.

etc.