Walker was again employed on military duties during the Mau Mau Uprising in the early 1950s. Treetops was offered as a lookout point for the King's African Rifles, but it was burned down by Mau Mau fighters on 27 May 1954. Walker built a bigger hotel at the same location in 1957, and business prospered - encouraged by public interest in the accession of Elizabeth II some years earlier. His hotel business was featured in "National Geographic" magazine, and famous celebrities, including Charles Chaplin and Paul McCartney, visited the hotel. Walker also wrote a book about his life in Kenya, named "Treetops Hotel".