Person who has been on TV more than anyone in history is woman you likely have never heard of

The most regularly broadcast face in history is no famous actor, well-known news presenter, or long-lived celebrity. In fact, it's someone you have probably never heard of.

Carole Hersee racked up over 70,000 hours of screen time between 1967 and 1998, becoming a TV legend in her own right without ever moving a muscle.

This is because she was the face of the 'test card' on UK television sets, appearing as an iconic image whenever there was interruption in the broadcast.

With only three TV channels available and 24-hour broadcasting a long way off, this meant that hers was a face that every Brit knew for decades. She would appear on screen both overnight and during the regular gaps in daytime scheduling.

Hersee was no glamor model or or otherwise famous person; she was just an eight-year-old girl helping out her father George who worked at the BBC as an engineer. He had been tasked with updating their test card system, which helped people across the UK to calibrate a revolutionary new consumer product - the color TV.

Known as 'Test Card F', this image was displayed on all TV sets multiple times per day (BBC)

In the image, which is well-known among Brits over a certain age, young Carole sits at a chalkboard in a red dress with two slots of a tic-tac-toe game filled in. Next to her, perplexingly, is the slightly creepy doll known as Bubbles the Clown.

Interestingly, Bubbles had originally been colored blue, but the TV engineers decided he needed to be green to help with calibration.

While this might seem an odd choice of image to help people calibrate their new color TV sets, it had been carefully chosen to contain all of the primary colors necessary to ensure the screen was displaying the image properly.

This was just one of the many calibration tools present on screen, which also included the 'X' of her tic-tac-toe game. This could be used to ensure the image was positioned correctly, with the cross marking the center of the screen.

Surrounding the most televised face you've never heard of were a series of gray blocks and other colors to help technicians to set the right contrast on the TV, something modern electronics has thankfully made a thing of the past with image pre-sets that can be controlled from a remote - a device that Carole's image predates the popularization of by around a decade.

Carole's face was known by everyone in Britain (Ian Tyas/Keystone/Getty Images)

Speaking more than half a century after her picture was taken, now aged 66, Carole explained why her image was selected.

On the TV show QI, she said of her father: "He was helping to design test cards and it was just decided that a child would be better than an adult because there'd be no fashion, no makeup, to worry about.

"It just happened to be that dad had sent in some pictures of my sister and I, and the committee decided, 'well we might as well stick with his children'."

However, Carole's reign as the face of disrupted broadcasts largely came to an end in the late 1990s, when 24-hour broadcasts became the norm on UK TV channels. Her test card ceased to be used entirely by 2012, when the country switcHed to digital broadcasts.

Despite the many years since the picture was taken by her father George, Carole still holds onto Bubbles the Clown, her co-star and only competition for most-televised face in all of human history.