A subscription purchased for just $ 30 (£ 22) can be worth as much as $ 50 million (£ 37 million).
The drawing in question was purchased by an anonymous guy in his sixties from a house sale in Concord, Massachusetts, USA, in 2016.
It sat in his house for a few years until Clifford Schorer, an American specialist in old masters and senior partner at London art dealer Agnews, fell over it.
To his amazement, he thought he might well have looked at an original by the 16th-century German Renaissance artist Albrecht Dürer.
In a speech to The Art Newspaper, he said: “It was an incredible moment when I saw Dürer.
“It was either the biggest forgery I’ve ever seen – or a masterpiece.”
Over the next two years, experts sought to authenticate it, and they did so by determining that Dürer’s ‘AD’ monogram was marked with the same ink as the drawing – which he did with more than 20 other works between 1501 and 1514.
The drawing also included a tripod and ring watermark, seen on more than 200 sheets used by Dürer.
The unknown drawing, which has been given the title The virgin and the child with a flower on a grass bench (1503), is thought to be a preparatory sketch for The Virgin among a multitude of animals.
The drawing had been in the collection of architect Jean-Paul Carlhian, who died in 2012, followed by his wife Elizabeth three years later.
The family thought the drawing was a 20th-century reproduction, and the Carlhian daughters jokingly said to the buyer at the house sale, “Oh, so you want the Dürer?”
Schorer negotiated a deal with the buyer before it was approved, and he has received an advance of $ 100,000 (£ 75,000), which he has used to pay off his credit cards, take over his house, buy a new car and make a generous donation to its church, according to The Times.
The drawing is currently on display at Agnews Gallery in London until 12 December, but the plan is to sell it in the long term.
Schorer believes the drawing ‘could get a record price’ of around $ 50 million – so it’s worth keeping your eyes open the next time you’re in the car (and learning a lot about how to identify works by great German Renaissance artists).