The history of this specimen is known. 1960 to 1993 was part of a collection of Swiss cars, Mr. Walter Grell Sen. Then it was sold and with the support of Bugatti experts was performed a restoration, all documented, concluded in 2000.
Since then, this little beauty has been used by the current owner for 20 years, has participated in rallies and has been published with various articles on Swiss Classics, a well-known Swiss magazine, not only that, the car is also published on the first page of the book Bugatti Type 40 "written by Barry Price and Jean Louis Arbey.

In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick

All documents confirm that the chassis number is 40237 and the engine number is 124. Among other things, the 124 appears on multiple components of the vehicle, such as the engine sump, gearbox, chassis, and front axle. 
Most of the previous owners of the car are known and the plates follow this ownership.
In addition to the restoration documentation there is the car's registration in the Hugh Conway archives, the Bugatti Owners Club England (BOC) and the Swiss Bugatti registry published by brand specialist Hans Matti. 
Interesting is a vintage photograph of the previous owners and a photo of Bugatti 40237 in front of the Bugatti residence in Molsheim, France.

In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick
In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick
In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick
In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick
In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick
In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick
In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick
In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick
In one of the Swiss vaults there is a very rare Bugatti T40. The car is offered for sale by a well known Broker named Kelly Dietrick

All publication details were provided by the broker handling the sale of this Bugatti T40 Sport, Kelly Dietrick, owner of the Philadelphia, Pennsylvania based company, "Kelly Dietrick Exceptional Car Broker" specializing in exceptional cars from exceptional collectors around the world.  Steam to Sportscars. Pre War/Post War, Race, Rally and Tour.

https://www.oldcar24.com/annunci/29142/bugatti-type-40-located-in-switzerland