After opening with a bogey in pleasant morning conditions, Ko made four birdies between holes two and 11 before dense drizzle settled in and birdie chances were limited.
Twenty-two years later, Hall is the pride of English golf, just as Faldo was.
Hall finished up with her only bogey of the day on the eighteenth but never looked likely to allow her lead to slip and joined Dame Laura Davies, Allison Nicholls, Catriona Matthew and Karen Stupples as a British-born victor of the British Open.
New Zealand's Lydia Ko could not summon the fast finish she needed at golf's Women's British Open at Royal Lytham to finish in a tie for 11th, 11 shots behind surprise home victor Georgia Hall.
She became the first English player of either sex to win a major at Royal Lytham since Tony Jacklin won the 1969 British Open.
Phatlum, who had started the day with a shot advantage, eventually fell short after a costly double-bogey on the pair's 71st hole of the tournament.
It put the two-time major victor tied for eighth at five-under par overall, with leader Pornanong Phatlum of Thailand at 10-under.More news: The royals share their sweet birthday messages to Meghan
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An errant drive on the eighth led to a bogey for Phatlum, and Hall moved into a share of the lead thanks to a birdie from 10 feet on the 13th.
On Saturday Phatlum admitted she had been singing Thai pop songs in her head to remain calm and the world no. 97 showed good control of any nerves as she bounced straight back to re-take the outright lead with a birdie on the second.
But Hall staged a great back nine charge with three birdies in four holes from the 13th, the 25-footer at the 16th earning the lead for the first time.
Atthaya Thitikul was the only amateur to make the cut, and her reward was to win the Smyth Salver. It added up to a solid 3-under-par 69 and the prospect of a first win on the LPGA Tour, let alone a first major title.
"It is too good to be true", Hall said.
"It's the British Open, you're going to get a little bit of drizzle and you just have to manage that". "I was so happy".
Ryu So-yeon of South Korea was third on 13 under after a final-round 70.