Now that the first week of the big spring auctions is over, Sotheby’s is wasting no time touting its sales in London next month, hanging highlights in its York Avenue galleries for collectors to peruse during the contemporary-art previews this weekend.

Knowing that today’s appetite for prime abstract paintings appears boundless, Sotheby’s expects a 1927 Mondrian that has not been on the market since the 1950s to be a star of its June 23 auction. This stark canvas, “Composition With Red, Blue and Grey,” was first owned by Harry Holtzman, an artist who helped found the American Abstract Artists Group, an influential organization that espoused the principles of European Modernism, and who was a friend of Mondrian’s and an expert on his work.