The first Mustang built, which was sold accidentally, is being reunited with its original seller Friday after 55 years.

Harry Phillips, who worked at George G.R. Parsons Ford in St. John's, Newfoundland, Canada, unwittingly sold the car to an airline pilot named Stanley Tucker. The car should never have left the lot, as it was a pre-production example intended to generate interest, not wind up in the hands of customers.

It succeeded in its original mission, as the dealership kept the sold car on the lot to drum up more attention. Tucker visited his Mustang regularly to make sure it wasn't any worse for wear, Phillips told the Detroit Free Press. Customers fawned over the new pony car, which was fast becoming an American darling.

As its popularity skyrocketed, Ford came calling on its pre-production demos. That's when the company learned that No. 001 had been sold to Tucker. 

"The serial number didn’t mean anything to us," Phillips told the paper. "We didn’t realize the significance of the car 'til Ford came looking for it."

Ford eventually talked Tucker into trading in Mustang number one in on Mustang number one million, a loaded 1966 convertible, at which point the first Mustang ever built made its way to The Henry Ford Museum, where it sits today.

Thanks to his granddaughter, Phillips is getting a trip to Dearborn to visit the Rouge plant and tour the museum. Her social media campaign, "Send Harry to the Henry," caught the attention it needed to score VIP tours for her, her mother and Phillips.