Although my publications include some work on sculpture, silver, jewellery, paintings, drawings, and prints, on heraldry and flags, on Renaissance iconography and emblematics, and on the history of collecting, my main research activity is in the field of European Renaissance ceramics, and particularly Italian maiolica. I have been publishing in this area regularly since 1984. This is a field of study which has to take account of approaches from art history, from material culture studies, from heraldry and genealogy, from archaeology, from analytical science, and from archival research. I have published collections of Renaissance ceramics for the British Museum, the National Gallery of Art (Washington), the Musei del Castello Sforzesco (Milan), the Fondazione Cassa di Risparmio di Perugia, the Detroit Institute of Arts, the National Gallery of Victoria (Melbourne), and the Metropolitan Museum of Art (New York), as well as three important private collections. My book Italian Maiolica and Europe, incorporating a catalogue of the post-Classical Italian pottery in the Ashmolean Museum, was published in the summer of 2017 and The Golden Age of Italian Maiolica-Painting in 2018..
I have been interested in the history of the collecting of maiolica and other works of art, especially by American collectors and museums from the years after the Civil War to the Second World War. I take the view that to understand the history of collecting you have to be interested in the art market and that that means recording and analysing the history of prices paid both by collectors and museums, as well as focusing on the role of dealers. In 2012 I was a Senior Fellow at the Frick Center for the History of Collecting in New York pursuing these issues. One outcome was a provisional list of the maiolica collection of John Pierpont Morgan, one of the largest and finest ever assembled in the USA; this list is too imperfect for formal publication but is made accessible here in the hope it may be useful to those interested in the subject.
I also compiled, in 2012, with the collaboration of the staff of the Lehman Collection at the Metropolitan Museum, a set of Addenda and Corrigenda to my late friend Jörg Rasmussen’s Italian Majolica in the Lehman Collection (1989).
I have lectured and taught widely in the UK, Continental Europe, the USA, and Canada. Since 2008, I have lectured at the British Museum, the V & A, the Society of Antiquaries of London, the Potteries Museum (the annual Reginald Haggar lecture), the Northern Ceramic Society, the University of Aberystwyth, and the University of the Creative Arts at Farnham; at the Istituto di Studi Rinascimentali (Ferrara), in Pesaro, Perugia, Gubbio, Deruta, Faenza, Assisi, Padua and Florence; at the Louvre; at the Frick Collection and the Bard Graduate Center in New York; in São Paulo, Brazil; and at the University of Warsaw.
In 2019 I co-organised an exhibition held at Palazzo Madama, Turin, La maiolica italiana: specchio del mondo rinascimentale, and another, Raphael ware: i colori del Rinascimento, at the Palazzo Ducale, Urbino.