The unknown portion is Vera Dalton: (Vera Dalton x Piccadilly). The color is described as white with pink splashes, with a cream reverse. Spreading, medium habit. Loose, cupped form. Slight fragrance. Referenced from 'Encyclopedia of Rose Science, Three-Volume Set'.
I am still not quite clear which was the seed and the pollen in that grandparent. is it... Champagne Cocktail x (Colour Wonder x {Vera Dalton x [Vera Dalton x Piccadilly]})
And what page of the Encyclopedia of Rose Science is it on please.