A Rolls Royce used for 22 years by Princess Margaret is going under the hammer at Imperial War Museum Duxford.
The bespoke Silver Wraith II is believed to have carried the Queen, Lady Diana Spencer and Ronald and Nancy Reagan during its time as a royal vehicle.
It belonged to Princess Margaret until her death in 2002 and is now being auctioned by H&H Classics on 26 May.
The auctioneers have estimated that the 1980-built vehicle will sell for £45,000-£55,000.
Damian Jones, Head of Sales at H&H Classics, said: "This is a very special, very important and low mileage Silver Wraith II which surely belongs in a museum.
"It is offered for sale with copy build records, service invoices and a wealth of period photos."
The car is one of only 2,135 built by Rolls-Royce, and was specially modified for Princess Margaret.
For example, the rear seats are mounted as low as possible because the Countess of Snowden, as she was also known, was only five foot, one inch tall.
Her widower, the Earl Snowden, sold the car to its current owner following Princess Margaret's death.
Its last official duty was to carry members of her family to her funeral in St George's Chapel, Windsor.