London ? It was the equivalent of finding an old Picasso or an unknown Beatles tape hidden away in your uncle’s attic.

Relatives of Dr. Harold Carr found an extremely rare 1937 Bugatti Type 57S Atalante — a Holy Grail for car collectors — as they were going through his belongings after his death.

The dusty two-seater, unused since 1960, didn’t look like much in the garage in Gosforth, near Newcastle in northern England.

But only 17 were ever made, and when it’s cleaned up and auctioned in Paris next month, experts believe it will fetch at least $4.3 million and possibly much more.

Bugatti once represented the height of motoring achievement. The supercar was so ahead of its time it could go up to 130 mph when most other cars topped out about 50 mph.

This particular car is even more valuable because it was originally owned by Earl Howe, a prominent British race car driver, and because its original equipment is intact, so it can be restored without relying on replacement parts.