All that can presently (July 2022) be gleaned about
Dora Clifford from sheet music covers and by Internet searching is that she was presumably an English dancer who has been featured on 2 works published between 1898 and 1919.
Her portrait on the left is taken from
Modesty (1919) music by
Alan Macey, and published by
W. H. Broome, London, England.
Surfers are welcome to contribute any further information about this performer.