Her memoir, The Private Life of a Country House (1912–1939), recounts her childhood years at Pilgrims Hall, and forms a detailed account of upper-middle-class family life in a small English country house with servants before the Second World War. It first came out in 1980 and has since been reissued five times; the 2011 edition is associated with the National Trust. The Sunday Times describes it as a "minor classic",Quoted on back cover of Severs D. 18 Folgate Street: The Life of a House in Spitalfields (Random House; 2011) () and a review of the first edition states "The charm of this book is that so many of the details of everyday life come alive and the more ordinary, prosaic things take on their true importance ... Reading it is rather like peering through the windows of a long-forgotten doll's house." Her recollections have been quoted by several recent texts;A few examples are The Death of Rural England: A Social History of the Countryside Since 1900 by Alun Howkins (2003), Nanny Knows Best: The History of the British Nanny by Katherine Holden (2013), Country House Society: The Private Lives of England's Upper Class After the First World War by Pamela Horn (2013) and The Country House Servant by Pamela Sambrook (2013) Pamela Sambrook writes that Lewis is "particularly successful at retrieving the memory of domestic trivia."
