By 1974 the rate of destruction of the country house had come to a near standstill. This was due not just to stricter application of legislation, but also the high-profile Destruction of the Country House exhibition held in 1974 by the Victoria and Albert Museum. Having preserved the house for future generations, Knowles died suddenly that year in London on 13 July 1974 at the age of 59. He is buried in the churchyard of St. James Avebury, next to the house which he had lovingly restored to ensure its survival.