All that can presently (September 2022) be gleaned about Minnie Duncan from sheet music covers and by Internet searching is that she was presumably an English music hall performer who has been featured on 2 works published between 1899 and 1904.
She is known to have been part of the music hall coster double act "Duncan and Godfrey" (Arthur Godfrey)
Her portrait on the left is taken from a photographic print ca. 1910.
Surfers are welcome to contribute any further information about this performer.