The 20-year-old from Kettering started the final round with a one-shot lead over American Brittany Lincicome and South Korea’s Ryu So-yeon, and produced a brilliant, bogey-free 66 to finish on 19 under par at Tiburon Golf Club.
Hull had six birdies on the outward nine and three on the back nine en route to a new tournament scoring record, previously set in 2015 by Cristie Kerr at 17 under.
Hull and Ryu were locked together on 18 under with two holes to play, but a two-shot swing at the par-five 17th – Hull rolled her approach up for birdie while Ryu found a greenside bunker and could only manage a bogey – turned proceedings decisively in the Briton’s favour.
Ryu admitted to making a mistake with her shot selection.
“The good thing is…