"I first played this tournament in 2012 and, since then, it's become the one that I want to win", said the 2011 US Women's Open victor, who added a second major at the 2017 ANA Inspiration.
Pornanong, a 16-time victor on tours in Thailand, Asia and Europe, admits she has been inspired by the Jutanugarn sisters - Moriya and world number one Ariya - who have boosted women's golf in her home country.
His daughter was born during the 1996 Masters won by English golfer Nick Faldo at Augusta, Georgia, and she was named as a tribute to that victory.
Hall's victory comes one year after she finished T3 at the 2017 Ricoh Women's British Open at Kingsbarns.
She represented Europe at the Junior Solheim Cup in Colorado in 2013, and a year later she lined up alongside Bronte Law and Steph Meadow in the Great Britain and Ireland team at the Curtis Cup.
Georgia Hall poses with the trophy after winning the 2018 Women's British Open Golf Championships at Royal Lytham & St. Annes Golf Club, north west England, on August 5, 2018.
But Hall chose the ideal moment to showcase her best golf and took the lead at exactly the right moment, sinking a flawless 20-foot putt on the sixteenth after Phatlum had found the green-side bunker.
Hull tapped in for a bogey - her first of the day - at the last hole to clinch a two-shot victory over Pornanong.
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Phatlum carded a composed three-under-par 69 at Royal Lytham & St. Annes, while England's Georgia Hall matched the score by sinking a 10-foot birdie at the last.
Trailing Phatlum by a shot overnight, the 22-year-old from Bournemouth held her nerve as the pair traded birdies in a compelling contest that effectively turned in to matchplay on the back nine.
Phatlum, who has four runner-up finishes on the LPGA Tour but has never won in almost a decade of toil, will head into Sunday's final round at 13-under 203.
Hall usually has her boyfriend, Harry Tyrrell, on her bag, but she made a decision to replace him with her father at Royal Lytham, and the move paid off as she claimed a memorable two-shot win and the title of Women's British Open champion. I was loving it deep down, hitting the shots under pressure.
Hall fired birdies on Nos.
However, the Thai bogeyed the eighth and Hall moved level thanks to a birdie on the 13th. "I was so happy".
To remain ahead, Phatlum birdied four of her first 10 holes and dropped her only shot of the day with a bogey on the par-three 12th.
With her win, she becomes the fourth Englishwoman to win the Championship and first since Karen Stupples in 2004.
It was also an emotional win as her grandfather is not well. "I felt like I putted my par putts really well, but the birdies putts weren't dropping that much, but to have a bogey free round especially at a major, I will definitely take it, so hopefully I have a lower one tomorrow. I've come this far, so all I do now is put on my best play", she said.