Here is my transcription of the performance by Lady Maisery.
https://www.youtube.com/watch?v=faX4mzC5NCw

THE CHANGELING'S LULLABY
(Words, Gavin Davenport, Tune, Jess Arrowsmith)

CHORUS
Hush awhile, hush awhile, sleep now for me.
Lay yourself softly if my babe you be,
Or did some fairy creeping from your crib steal you sleeping
And leave me a creature that’s nothing of me?

My bairn was often silent and would sleep through half the night.
And he greeted me every morning with a smile so full of light,
But now you are much altered and do bawl the whole night through,
So hush a while, my darling, so I might know it’s you.

Your father says you’re not his own nor any child of man’s,
But I think you have your father’s smile, your father’s gentle hands,
And I pray that you will love me like your father used to do,
So hush awhile, my darling, so I might know it’s you.

Your skin was like the lily white, and as soft as winter snow,
Not like some screaming devil with his scarlet face aglow
That sails across the wind’s soft skies (?) that creep the casement through,
So hush a while, my darling, so I might know it’s you.

If your mother couldn’t love you, though a fairy babe you be,
I would take you to the forest and I’d leave you ’neath yon tree,
But while you are all I have, love, I still will cleave to thee,
For whatever else you are, love, still your mother’s love you be.

---

You'll notice I made some changes:
was often silent and would sleep through half the night
Or did some fairy creeping
If your mother couldn’t love you

I wasn't sure of this line: That sails across the wind’s soft skies (?) that creep the casement through

Any thoughts?

-Joe-