Three photos, the first a single flower from an earlier blooming, the second a pair of flowers, the third a mericlone of an awarded alba form. The non-alba does not have very good shape but is about a third larger than the alba form. It is huge compared to other walkerianas I've seen.
I've had both for quite some time and when we last moved lost all my records and just don't remember where either came from. I think the alba I got as a very small seedling, but that's about all I remember.