The couple were on track to watch their 4yr-old easily win the group 1 New South Wales Breeders' Challenge in 1.49.4.
The victory capped what has been a remarkable ride for Duncum and Masson since they got their first winner in 2014.
Their first taste of horse ownership was a unique and successful one when Thebestlove won from Tim Butt's stable at Addington.
Duncum had bought a share in the horse for the couple and had tried to keep it as a surprise for Masson until the day of the race.
The surprise was ruined when some eagle-eyed harness fans spotted Duncum's name in the ownership and made inquiries to a mystified Masson.
Thebestlove won his first start, which turned out to the first step in the couple building a mini harness-racing empire.
"At the moment I have got 12 horses and I have to say at the moment I think I am the luckiest owner that I know of, because of all those horses that have raced, there is only one so far that hasn't got two wins," Duncum said.
Duncum and Masson have continued to build their interest as a retirement hobby.
"I wasn't in a position to be an owner or be involved until more recently until Bruce and I decided it would be a nice way to spend some time and socialise with people," Duncum said.
"We have met some wonderful people and have had some delightful results."
Masson worked for the DCC's water division for 44 years until retiring nine months ago.
He and Duncum have most of their horses in Tim Butt's Menangle stable.
They own shares in smart types including Franco Landry, Mac Almighty, Gentleman Sir and Regal Major.
Their winning ways looks set to continue with Let It Ride soon off to the Queensland winter carnival.
The 4yr-old will be accompanied by Field Marshal, who ran second in the Len Smith Mile on Sunday behind Cruz Bromac for another Otago couple, Syd and Shona Brown.
