When the Horner family took up residence at Mells Manor House, the Library, or Book Room, was refurnished with shelving designed by Herbert Jekyll (1846–1932), husband of Lady Horner’s younger sister, Agnes Jekyll (née Graham; 1861–1937), and brother of the influential horticulturist and garden designer Gertrude Jekyll (1843–1932). 

In 1923, William Nicholson, who already knew Frances Horner, moved to the Old Manor House in Sutton Veny, Wiltshire, which had been gifted to his wife by her father. Although it had recently been renovated, further work was undertaken when the Nicholsons moved there. During that time, the couple spent a week at a cottage at Mells. It was also at this time that Nicholson painted the present trompe-l’oeil door. Situated in the north wall of the Book Room, it gave access to a small washroom and lavatory. The door was painted employing stencils and sgraffito to give the impression of tooled calf-leather bindings. The scheme comprises three giant-sized books entitled Spanish Castles, Rules of WHIPPERGINNY and Cuccu.

Whipperginny was the title of a book of poetry, published in 1923, by Nicholson’s son-in-law, Robert Graves (1895–1985), who had married his daughter, Nancy, in 1918. Nicholson produced designs for the book, replicating the lettering on its cover in the central volume of the door.¹ Whipperginny was also a card game – hence the ‘rules’ in Nicholson’s title and the decoration of the spine with playing cards. The left-hand volume, Spanish Castles, depicts at the top of the spine the emblems of Castile and León – the castle and the lion – although the precise literary reference is unknown. Cuccu, the title of the book to the right, is the old English name for the cuckoo; a pair of cuckoos appear at the top of the spine with eggs in their beaks – a reference to the cuckoo’s habit of removing eggs from other bird’s nests in order to colonise  them. Further down the spine, below the title, are depictions of birds’ feathers – again referencing the cuckoo. The literary source – if there is one – remains unknown but it may, for example, relate to either of two poems by Graves published in his anthology Country Sentiment, of 1920, ‘Pot and Kettle’ and ‘The Voice of Beauty Drowned’, both of which feature the cuckoo.