The winner of some 20 career Australasian Tour titles, Stanley held firm against one of this venues greatest champions, New Zealands Bob Charles, beating the lefthander with a par on the first hole of a playoff after the two had finished at 6-under 278 in regulation.
He also held off American legend Jack Nicklaus, who ' for a time ' looked to be in serious contention for his first British Seniors title, until he faltered down the stretch, finishing three shots off the pace at minus-three.
Entering the green at the 18th, the title appeared to be a lock for Stanley, as the 52-year-old was one better than Charles at minus-five.
However, a three-putt bogey put a quick end to that story, and gave new life to the 66-year-old Charles, who in 14 previous Opens, had won twice, finished second four times, and on only two occasions had finished outside the top-6.
Yet, on the first extra hole, Charles put his tee shot into a bunker, and could do no better than bogey for the hole.
Following a stock par, the title was Stanleys.
I was thinking of Retief Goosen when he missed the putt at the last in the U.S. Open, Stanley recounted of his bogey which led to the playoff.
For the day, Stanley shot 69, while Charles posted a 68.
American interest had been brewing all week, as Nicklaus was gunning for his first win on European soil since the 78 Open Championship at St. Andrews.
It climaxed on Sunday, as Nicklaus eagled the par-5 12th to move to 4-under for the tournament, just two strokes off the pace at the time.
But is was to be undone at No. 15, when the Golden Bear made bogey to ultimately fall out of contention with a 69.
I was disappointed with my finish, said Nicklaus following his round. I was 1-under on the front nine and felt if I could play the back nine in 4-under, Id have a shot to win.
I started it well with a birdie at No. 10 and an eagle at the 12th, and that put me close to my target. But as it turned out, it wouldnt have been enough anyway.
Full-field scores from the Senior British Open