Harper, now attached to Archerfield Links, was a Musselburgh member when he won the 1999 Scottish Boys' Championship at West Kilbride.
And he used his local knowledge to good effect to share top spot in yesterday's Regional Qualifier with a five-under-par 66 on the Monktonhall course.
"When I was 15 and 16, I used to go round here regularly in the high 60s and it was nice to produce another good score in an event like this," said the 28-year-old.
After a bogey at the first, Harper bounced back with six birdies – at the fifth, seventh, eighth, 11th, 12th and 14th.
"There were a couple of things that made a difference," he added. "I had a new Titleist driver in the bag, having cracked my old one in April and taken until now to find one that I like.
"I was also using an old set of irons that served me well in the past. I made it to the Local Final Qualifying three years in a row about a decade ago and it's great to be going back there again.
"To play in The Open has been my dream since boyhood but I was determined not to put any pressure on myself – I just went out and relaxed."
Harper's sparkling score was matched by Stephen Gray, the 36-year-old Hayston pro, who is one of the most popular players on the Tartan Tour.
Gray, who came within a shot of playing at Troon when Todd Hamilton won in 2004, also signed for six birdies, the last of which was a tap-in at the 15th.
On a course that was once again in pristine condition for this event, Swanston New's John Gallagher finished third on 67, describing his round as "the best of my professional career".
After three-putting the tenth to drop his only shot of the day, the former Scottish amateur champion made a good up and down at the next to save par and ended up bagging five birdies.
"I didn't make any mistakes and also putted nicely," said Gallagher, who is now hoping to play in the Local Final Qualifying at Fairmont St Andrews next week.
"We played there on the EuroPro Tour so that would probably be the best of the four courses for me," he said.
Playing with Gallagher, Zhiquin Lam, a 21-year-old amateur from Singapore, birdied the last two holes for a 69, a score that was matched, among others, by Baberton's Paul Ferrier.
The former Scottish Boys' champion highlighted his round with an eagle-3 at the seventh, where he hit his 6-iron approach to 15 feet and holed the putt.
"This is only the second time I've played in the Regional Qualifying and it's nice to get through," said Ferrier.
Craig Gordon, the former Ratho Park star who is now attached to Edinburgh Golf Centre, also claimed one of the 17 spots up for grabs with a 70. He was relieved that a bogey at the last hadn't proved costly.
But a lost ball at the fifth saw Craigelaw's Mark Hillson miss out by a single shot on a play-off for the last berth, Paul Drake of Pumpherston also fell one short along with former Mortonhall man David Patrick, while Zack Saltman missed out on the chance to join his big brothers at the next stage after a 73.
Musselburgh's Myles Clapperton missed out after a 77.
At Goswick, Marriott Dalmahoy's Mark Kerr birdied three of the last five holes as he made it through for the second year running there with a one-under 71.