Task: Question Generation
Input (English): Passage: Sandringham is recorded in the Domesday Book as "sant-Dersingham" and the land was awarded to a Norman knight, Robert Fitz-Corbun after the Conquest. The local antiquarian Claude Messent, in his study The Architecture on the Royal Estate of Sandringham, records the discovery of evidence of the pavements of a Roman villa. In the Elizabethan era a manor was built on the site of the present house, which, by the 18th century, came into the possession of the Hoste Henley family, descendants of Dutch refugees. In 1771 Cornish Henley cleared the site to build a Georgian mansion, Sandringham Hall. In 1834, Henry Hoste Henley died without issue, and the estate was bought at auction by John Motteux, a London merchant. Motteux was also without heirs and bequeathed Sandringham, together with another Norfolk estate and a property in Surrey, to the third son of his close friend, Emily Lamb, the wife of Lord Palmerston. At the time of his inheritance in 1843, Charles Spencer Cowper was a bachelor diplomat, resident in Paris. On succeeding to Motteux's estates, he sold the other properties and based himself at Sandringham. He undertook extensions to the hall, employing Samuel Sanders Teulon to add an elaborate porch and conservatory. Cowper's style of living was extravagant—he and his wife spent much of their time on the Continent—and within 10 years the estate was mortgaged for £89,000. The death of their only child, Mary Harriette, from cholera in 1854 led the couple to spend even more time abroad, mainly in Paris, and by the early 1860s Cowper was keen to sell the estate.
Output (English): What is the full name of the estate that Cowper was keen to sell by the early 1860s?