Knebel hung onto the car for over two decades, maintaining it himself, including performing a full engine rebuild in 2006.
Soon after this, the Porsche was imported to the UK, where its fourth owner registered it on British plates for the first time in its life.
Its mechanical well being was entrusted to specialist Lee Maxted-Page and the car even achieved a second-place finish on the 2007 Tour de España-Portugal.
In 2010, the 356 passed to its fifth owner and current owner. It joined a large private collection and was entered into the Salon Privé Concours d'Elegance in 2012.
It’s estimated that this 85,798-mile 356C will sell for £550,000-650,000
Some lucky person will become owner number six next month.
The 356C Carrera 2 2000 GS was almost double the price of the standard model, making it Porsche’s top offering in 1964 – and it was the marque’s first car with four-wheel disc brakes.
It’s in concours condition, has 85,798 miles on its odometer, and will be sold with its history file plus original hand books and manuals.
“Cars of this type don’t come to market very often, and right-hand drive models hardly ever appear,” adds Whale.