It all began with a child’s accidental phone call to a secret US air force number. The rest is Christmas history.

In early December 1955, the phone rang at an air base in Colorado Springs. The officers on the watch floor of the Continental Air Defense Command (CONAD) – who were defending the skies above the US and Canada – stiffened.

The Cold War was in full swing and tensions were running high.

The command’s director of operations Colonel Harry Shoup answered the call. On the other end was a child’s voice asking: “Is this Santa Claus?”

According to the colonel’s daughter Terri Van Keuren, now 75, her father initially thought it was a prank, and replied: “I’m the commander of the Combat Alert Center. Who’s this?”

In response, the child started crying and asked if he was one of “Santa’s helpers”.

The colonel then decided to play along, replying that he was indeed Santa Claus and mustering a convincing “ho-ho-ho”.

This surprise call started the nearly 70-year tradition of the Santa Tracker, which allows children around the world to track the whereabouts of Father Christmas via a livestream and a phone line answered by volunteers.

It is now run by CONAD’s successor, the North American Aerospace Defence Command (NORAD).

But how did a child seemingly get the phone number of a colonel in the US air force?

The American department store Sears had printed an advert in a local newspaper telling children they could call Santa, Terri explains.

“They had printed one digit wrong in the phone number. And it was dad’s top secret number.”