Unfancied by punters, the seven year-old had a spring in her step as she skipped away from the opposition to win the 1200 metre sprint by a length and three-quarters.
Two Blue (images Steve Hart) has the overall record of eight wins and 16 placings from 38 starts with prizemoney soaring beyond $637,000.
"Paul just rode her an absolute treat," Buchanan said. "I can't describe it. It's awesome."
"She's so tenacious. She loves being a racehorse.
"If you watch her she'll run past them again after the post. She just has that incredible desire to win."
King has gone close aboard Two Blue on numerous occasions in black type affairs, finishing runner-up in the Group II Golden Pendant and several other stakes events before finally breaking through for a deserved Group victory.
"She was unlucky last preparation," King said. "In quite a few races she ran a lot of good seconds against some good horses.
"I said to Kristen that this time around I think she has improved. I think she is in for a lot better of a prep this time around and that was proven today with her winning a Group II."
Buchanan has plenty of options of an in-form mare early into a campaign but with a Group II success in the bag, a crack at the Group I Robert Sangster Stakes (1200m) in South Australia is now under consideration.
Two Blue is the best of three winners from Blue Booty, a metro winning mare by Personal Flag (USA) from the family of Group I winner Magnitude.
She is the fourth stakes-winner for Dubleo, who started his srud career with Vinery Stud, but is now with Cangon Stud Farm.