Key of C. And yes, the careful music-history knowledgeable listener will discern the double-entendre in the song title.

Following the path unmarked
To the highest of Kings
We tread with shepherds
And like magi we bring

Bright in the dark, the star shines light where its due
Like the wise men we place our gifts before you
Rejoice for the light of the big star
Praise be the King of near and far
Choirs sing in the light of the big star
Hallelujah, King of my heart

Laden with burden
We fall to our knees
To honour this child
Whose yoke is our ease

Bright in the dark, the star shines light where its due
Like the wise men we place our gifts before you
Rejoice for the light of the big star
Praise be the King of near and far
Choirs sing in the light of the big star
Hallelujah, King of my heart

Peace on Earth to people of good will
Peace on Earth to people of good will
Glory to God in the highest!

Bright in the dark, the star shines light where its due
Like the wise men we place our gifts before you
Rejoice for the light of the big star
Praise be the King of near and far
Choirs sing in the light of the big star
Hallelujah, King of my heart