Collecting and cataloguing art 1945–1978
Seilern returned to London at the end of the war to live in a great gloomy house he had acquired at 56 Princes Gate, South Kensington, where he rarely opened the blinds and electric light was largely eschewed as he said it distorted colours in pictures. At Princes Gate the ground floor was devoted to his enormous art library, and therefore pictures were hung mainly on the first floor, well-spaced, as in a museum. Other rooms in the house, of course, also held pictures: for example, on the second floor there was a charmingly decorated room called the card-room, which was apparently rarely shown to visitors but in which, eventually, he hung his Tiepolos, and behind this was a private study, hung with a group of Impressionist pictures including a fine late Cézanne.
The war over, he resumed collecting works of art, buying them privately for the most part rather than at auctions, never from a photograph, and never when pressed by a dealer, pictures left 'on approval' frequently being returned. He devoted time to studying them in depth and cataloguing them accurately, though he was also a generous anonymous benefactor of public collections; for example, he lent to exhibitions held at the British Museum (he lent his Michelangelo drawings to the 1975 exhibition there – which he would otherwise not have done except that it was being held in honour of his friend Johannes Wilde), and in 1945 he gave the National Gallery anonymously a very fine full-length portrait of William Feilding, 1st Earl of Denbigh by Sir Anthony van Dyck [NG5633] as well presenting anonymously to the British Museum in 1946 the majority of the important collection of Old Master drawings (some 1250 in number) belonging to Mr. Thomas FitzRoy Fenwick, which had been assembled by Sir Thomas Phillipps, 1st Baronet in the library at Thirlestaine House, Cheltenham, and which had been catalogued by Arthur E. Popham of the museum in 1935 and bought by Seilern en bloc (Seilern retained about two dozen drawings). The proceeds of the sale of the catalogue of his own collection, when it appeared, would be given to the National Art-Collections Fund (now The Art Fund) and the National Trust.
Eventually his collection would come to include masterpieces not just by Rubens (32 paintings – oil sketches and modelli mainly, but also some of the artist's copies of Old Masters like Raphael's portrait of Baldassare Castiglione – and 20 drawings); 14 small copies by David Teniers the Younger after pictures in the collection of Archduke Leopold Wilhelm of Austria during his Governorship of the Spanish Netherlands in 1647–56, commissioned to make a series of prints for the book known as the Theatrum Pictorium first published in 1660; and 12 by Tiepolo (including six oil sketches for paintings for the Monastery Church of Aranjuez, south of Madrid), and pictures by Claude Lorrain, Degas, Van Dyck, Quentin Massys, Lorenzo Lotto, Magnasco, Manet, Francesco de Mura, Palma Vecchio, Parmigianino, Pittoni, Sebastiano Ricci, and Tintoretto. There were also drawings by Giovanni Bellini, Pieter Bruegel (one of the most important collections of his landscape drawings in existence), Hugo van der Goes, Fra Bartolommeo landscape drawings, Michelangelo, Parmigianino, Stefano della Bella, 30 drawings by or attributed to Rembrandt, Van Dyck, Canaletto, Francesco Guardi, Watteau, Degas, Cézanne and Picasso, and drawings and engravings by Albrecht Dürer. Surprisingly perhaps, he commissioned a ceiling painting in triptych form of The Myth of Prometheus for the entrance hall of his home in Princes Gate by his friend Oskar Kokoschka. He also possessed fine Chinese bronzes, Greek vases, Limbourg brothers manuscripts, Holbein manuscripts, and German and Austrian paintings. He is recorded as owning a three-quarter length pastel of his mother by Clemens von Pausinger (1894) as well as a signed and dated bust-length portrait of himself as a boy by Muller-Ury, which was unframed and stored in a cupboard. Starting in 1955 Seilern began the publication of a catalogue in seven volumes assisted by Fritz Grossmann of the most important parts of the collection, though he waited in vain for Wilde to produce catalogue entries on his important Michelangelo drawings.