Oh, Lorn - just a second thought.
I'd be tempted to try L. pumilum varieties 'Yellow Bunting' or 'Golden Gleam' instead... some little stored trivia has L. pumilum and its varieties down as the secret to Judith Freeman's success. (One of the many, I'm sure!). Despite being diminutive, it reportedly creates hybrids of great stature and bud count.
Results could be very different if using L. davidii just once as an outcross, but working with successive generations of L. davidii hybrids, I've found the orange and spotting to be very persistent. I can't imagine either would accentuate the lovely clean contrast of your lily. Not that seedlings wouldn't be pretty... they'd just be further from the character of your original, I think? L. davidii var. unicolor could be another option, but it's hard to find a good example - the ones I've seen tend to be rather 'looser', more willowy plants, with correspondingly less tight flower form....
(I have to add, I really don't feel qualified to comment, just passing on the thoughts and feelings that arise from this complete jumble of information that sometimes passes for 'knowledge' in my brain. ie.... I half remember a bit of everything, and then it recombines at high temperatures into weird, fantastical chimeras that have little relationship to reality or fact. Some days it's kind of fun. Obviates the need for recreational drugs
)
