A rare first edition of Brideshead Revisited and a photograph of the Queen having her portrait painted were among the items owned by the late Dowager Duchess of Devonshire which raised almost £2 million at auction.
An auction of Deborah Mitford's personal collection by Sotheby's raised £1,777,838 - three times the amount which was expected.
Hundreds of collectors gathered to watch the 450 items go under the hammer on Wednesday, with more than one thousand bidders taking part in the sale.
A rare first edition of Brideshead Revisited, given to the "Debo" by its author and her good friend Evelyn Waugh, fetched more than £50,000.
The popular novel, published in 1945, was sold for £52,500 at the all-day sale - more than double what Sotheby's had predicted.
Set in the period between the First and Second World Wars, the book is one of 50 early copies which were distributed to the author's inner circle prior to general publication, inviting their suggestions and revisions.
It is one of the rare few signed by Waugh, with the message inside reading: "Debo & Andrew | with love from | Evelyn | A very old fashioned story".
A photograph of Lucian Freud, grandson of Sigmund Freud, painting the Queen in his studio in 2001 was sold for £10,000 - more than 10 times what Sotheby's estimated.
The Duchess, also known as the Chatelaine of Chatsworth, was the youngest of the six Mitford sisters and died in 2014 aged 94.
Her sisters included novelist Nancy Mitford, writer Diana Mitford who married Sir Oswald Mosley, the leader of the British Union of Fascists, and Unity Mitford, who was close to Adolf Hitler.
Deborah's friends included former US president John F Kennedy, former prime minister Winston Churchill and the playwright Alan Bennett.
Her family said: "Deborah was always interested in and excited by the auction process, so we can guess how much she would have enjoyed today's sale.
"She would have loved the idea that many people from all over the world will now enjoy some of the pieces she lived with."
Most of the items up for auction hail from The Old Vicarage, the 18th century house in Edensor, on the Chatsworth Estate, where the Duchess spent the last 10 years of her life.
The most expensive item was a late 19th century gilt-decorated statue from Japan, which was brought to England by the Duchess's grandfather, Algernon Bertram Freeman-Mitford, and sold for £62,500.
Other notable lots included the Duchess's Elvis Presley memorabilia collection which fetched more than £4,000 and included a novelty singing and dancing Elvis telephone.
All prices include buyer's premium.