The catalogues are still relevant. The handwritten one records the pictures' dimensions, one facet that helps confirm their identity. The Hume picture list contains a description of the paintings, as above. We recently helped the Old Master Department of the Dorotheum auction house in Vienna, Austria who enquired about the provenance of that 'Titian' painting of Andrea Navagero, before its sale at auction at Christie’s on 3 May 1929 by the 6th Baron Brownlow. Hume's purchases were based on traditional connoisseurship that was often imprecise. The Andrea Navagero (below left) is now regarded as by an anonymous Venetian painter of the sixteenth century rather than Titian.
Said to be the portrait of Andrea Navargo - confusingly, the Navagero (alleged copy) looks very much like a younger version of Titian himself rather than extant portraits of Navagero!