Looking at the lip color and considering how the "muddying" you get from P. philippinense often affects its hybrids even a couple generations removed, I'm not convinced there's much (if any) philly in the background. I certainly wouldn't expect to see this much saturation, brightness, and clarity of color in the lip from a hybrid with 25% or more philippinense unless it was an extremely exceptional clone.
Otherwise suggestions that rothchildianum and sanderianum are in the background of this cross seem pretty reasonable to me. Roth would explain a lot of features, sanderianum would explain the petals and ovary. Although there are lots of stripes and color in the dorsal sepal, it wouldn't surprise me to find out there's some stonei or platyphyllum in there.