I was thinking maybe 'Sterling Star' when I was researching it. It looks like a photo in McRae's book and also a photo in one of my other books. Both photos look alike and show those elongated spots over about half the length of the petals. On the other hand there is no mention of spots at all in the Lily Register, but since it is an old lily (circa 1973) descriptions were pretty sparse back then.
Does that name ring a bell? There are so many white lilies with spots it is hard to say. But since you say it is old, then could be. The register does describe the height as 1-1.2 meters (3-4 feet, taller than your lily).
