Storico dell'arte (Plymouth 1889 - Londra 1970); conservatore del Gabinetto dei disegni e stampe al British Museum dal 1945 al 1954. Pubblicò tra l'altro: Catalogue of drawings by Dutch and Flemish artists preserved in the Department of prints and drawings, British Museum (I, 1932); A handbook to the drawings and water-colours in the Department of prints and drawings, British Museum (1939); The drawings of Leonardo da Vinci (1946); The Italian drawings of the XV and XVI century ... at Windsor Castle (con J. Wilde, 1949); Italian drawings in the Department of prints and drawings in the British Museum. The fourteenth and fifteenth centuries (2 voll., con Ph. Pouncey, 1950); Correggio's drawings (1957); Artists working in Parma in the 16th century (2 voll., 1967). La sua opera maggiore è il corpus in tre voll. dei disegni del Parmigianino (post., 1971).