A collection of 100,000 rare stamps put together by an aristocratic racing driver from Kent raised more than £3.5m in its first three days at auction.
Sir Gaiwaine continued his stamp collection after retiring from racing
Sir Gawaine Baillie was born in 1934 at Leeds Castle and began the collection during his boyhood on the estate, continuing nearly to his death in 2003.
The first of 10 auctions has been held at Sotheby's in London this week, with £3,528,697 raised.
Sotheby's estimated the final sale total for the collection would be £11m.
"The first of the Sir Gawaine Baillie sales has established that this is going to be a monumental series where new price levels will be realised at each sale," said the auctioneer's philatelic specialist Richard Ashton.
Star lots of Thursday's sale were an 1880 2s brown in a pane of 20 which fetched £240,800.
A King Edward II 2d Tyrian Plum which was estimated to fetch £20,000 to £25,000, raised £54,000.
Sir Gawaine's mother, Lady Olive Baillie, was the last private owner of Leeds Castle, which she bought in 1928.
Her son grew up to become an amateur racing driver, competing with famous names such as Stirling Moss and Jackie Stewart in the 1950s and 1960s.
His successes on the race track included beating three-time World Champion Jack Brabham in the 1966 British Championship.
Sir Gawaine's King Edward II 2d Tyrian Plum fetched £54,000
He also ran his own engineering business, HPC Engineering in Burgess Hill, Surrey.
After retiring from racing he returned to his boyhood hobby, devoting four hours to his stamp collection every morning.
The extent of the archive only came to light following his death, when Sotheby's was invited to view 280 albums in a vault.
It found stamps from Great Britain and the Empire dating from 1840 to 2000.
The collection is being put up for auction by Sir Gawaine's widow Margot and their two children.
"With the collection's dispersal at auction, thousands of collectors throughout the world will have an opportunity to acquire a vast array of rare and wonderful items," said Mr Ashton.