The Countess of Carnarvon was at WHSmith in Cornmarket Street, Oxford, for a book signing event on Saturday.
Her husband owns Highclere Castle, where television series Downton Abbey is filmed.
She was in demand to sign copies of her latest book, Lady Catherine and the real Downton Abbey.
She was accompanied by her husband Lord Carnarvon, the eighth Earl of Carnarvon.
The fourth series of the TV series started on Sunday, September 22.
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