Coachbuilt wonders will look back to a bygone era.

This year's Concours of Elegance at Hampton Court Palace on September 4-6 will celebrate a bygone era of unique coachbuilt cars by gathering a trio of one-off masterpieces.

Once upon a time, the well-heeled would by a car as a rolling chassis, and then take it to a specialist coachbuilder to finish the job off. It was like the customisation departments we see at high-end manufacturers today, only on a much more personal level.

Heading the display will be the Bugatti Type 57 Atalante Gangloff. The Type 57 was first unveiled in 1937 and was the first car built under the watchful eye of Jean Bugatti, the eldest son of the company's legendary founder Ettorre.

1938 Bugatti Type 57 Atalanta Coupe

Powered by a a 3.3-litre straight-eight producing 140bhp, like Bugattis of today the Type 57 easily out-did its rivals in the power department.

In February 1938 wealthy French industrialist Fernand Crouzet tasked coachbuilder Gangloff to create a bespoke Type 57. The resulting machine featured long rear wings, a bootlid-mounted spare-wheel mount, single back window, special bumpers and disc wheels.

The car survived the Second World War and was put to use as transport for the French Embassy in London and has since passed through a number of owners.

1957 Jaguar XK150S Bertone

Joining the Bugatti will be a Jaguar XK150 S Bertone, one of just three XK150 that were sent to renowned Italian styling house Bertone to bodied as prototype fixed-head coupés.

While three cars got the coupe treatment, each car got slightly different styling by Franco Scaglione. The car heading to the Concours of Elegance is chassis number two and was made on August 15, 1957. It hasn't been seen for decades and is thought to be the only one of the three that remains today.

1928 Bentley 4.5 Litre Drophead Sport

The final car in the trio is a Bentley 4.5-Litre Drophead sports coupé known as 'Mr. Fred'. Mr. Fred, one of just two cars of its kind that still exist today, is a product of Newport Pagnell coachworks Salmons & Sons – which later became the home of Aston Martin. Before turning its attention to cars, the company made high-quality horse-drawn coaches and dog carts.

The aluminium-bodied Bentley is a fine example of Salmons & Sons' unique craftsmanship, as is its wonderful mother of pearl instrument panel.

All three will be in the Main Concours display alongside a selection of 'future classics', Formula 1 cars, and a new 'Junior Concours' which will feature half-scale pedal, petrol, and electric cars.

Gallery: Unique Bugatti among rarities at this week's Concours of Elegance