Kevin John Cullen was a passionate believer in the quality of Margaret River wines and particularly for the potential to achieve one of the world's great Chardonnay growing regions. He established the International Chardonnay Tasting, now in its third decade, to enable the efforts of Margaret River to be compared alongside the best vintages from around the world. Kevin John anticipated that the lessons learned from these comparisons would inspire his winemaking team to optimise the quality of Chardonnay grapes grown to the Cullen estate vineyards.

Diane Madeline has found her oenological paramour. Kevin John is named after the estate patriarch and shares provenance with the most stately Margaret River Chardonnay. Grapes are picked at ideal physiological ripeness, after achieving healthy profiles of natural sugars. Acid levels in the fruit grown by Cullen are remarkable, with low pH and fine balance, making any additions for adjustment unnecessary. Chardonnay is harvested around the full moon to a cycle in accordance with the best biodynamic practices. Grapes are whole bunch pressed and spontaneously fermented in French oak barriques, two thirds of which are new, followed by partial malolactic and five months maturation.