Using this collection housed at the Art Gallery of Ontario as a case study, the catalogue discusses the function of miniatures, their material presence, the circumstances in which they were made and aspects of their later history. The homes and studios of the most successful painters, as sumptuous as those occupied by oil painters, often passed from one generation to another: here, one key property in Covent Garden is described and illustrated. In this book, for the first time, a number of specialist artists’ suppliers are identified, showing where ivory could be obtained and enamel plates prepared and fired. The links between enamelling for clock and watch faces and enamelling for miniatures are demonstrated. The illicit practice within the late nineteenth and early twentieth-century art trade of duplicating old miniatures, a topic generally avoided in the literature, is addressed here. Miniatures are difficult to display in museums, but recently-developed photographic methods of identifying pigments are also proving to be a way of introducing a new audience to this multilayered subject. Eighteen years after Ken Thomson’s death, there could not be a more opportune moment to highlight his collection.