Paph. Perseus
Paph. Perseus is a grex registered in 1925 by William R. Lee, after whom Paph. Leeanum and Paph. W.R. Lee are named. His collection was amongst the finest in England at the time, including a tremendous selection of paphs, of which Paph. stonei 'Platytaenium' was a part. This grex involves the normal suite of early contributors to complex paphs - insigne, villosum, boxalii, and spicerianum, although a branch of its family tree is unknown. It represents the first attempts at selective breeding for color, and was a very successful grex in its day; there are several clones awarded by the RHS and the Manchester Orchid Society in the 1920s and 1930s.
This clone, Paph. Perseus 'Stonehurst' AM/RHS, 1927, was shown by noted paph (and more importantly, Miltoniopsis) grower Robert Paterson. He is perhaps most famous for owning Miltonia Lycaena 'Stamperland', an aneuploid which, breeding as a tetraploid, is in the background of nearly every modern red Miltoniopsis. The remainders of his collection was purchased by Lows at his death, so it is possible that 'Stonehurst' was the actual clone used in your Paph. Joan Harris.
Paph. Joan Harris made its way to the US fairly early, with records appearing in the Massachusetts Hort Society Yearbook as early as 1936 being shown by an Edward Webster.
Give me some time and I can search around for Mrs. William Pickup as well...