The tureens, marked for Paris 1778-1780 and weighing 1411oz, formed part of a grand dinner service made for George III, Elector of Hanover and King of England, 35 pieces of which are already in the museum's collection.
The service has a long and complex history but, in short, it remained in Hanoverian family ownership until the 1920s when it was sold to two dealers, Cricthons of London and Gückselig of Vienna. Half of it was acquired by the Rothschild family and half by Louis Cartier.
Today the Rothschild element is divided between the Louvre and Waddesdon Manor. These tureens come from the Cartier part, which was sold by Sotheby's Monaco in 1979. They were then acquired by the gemmologist and artist-jeweller Alexandre Reza from whose collection Sotheby's negotiated the private sale.
Given that so many French royal services have been melted down, the Louvre intends to use the tureens and other pieces from this Hanoverian service, all of which carry Auguste's mark, to create a display of a table service à la française. It will be set up when the museum reopens its 18th century furniture section in 2013.
In the UK, private treaty sales by auctioneers have been around for some time, but in France where a law was only recently passed allowing auctioneers to conduct them, they are more of a novelty.