This rose is not pure white in colour. Have a look at Wagner's Roses website for another image, Wagner's description : 'Custard Cream is an Australian originated floribunda from breeder Richard Walsh, with white flowers; as the white blooms blend from cream to light yellow tones and at other times are flushed with pink, flowers form in clusters throughout the season. The plant has upright growth with a medium height of 120cm and a width of 90cm, it has semi-glossy foliage.'
This is an interesting rose from R & R Walsh - there is a range in the colour blend showing in other images taken in the trial garden.