Auction introduction: Spanning six centuries of European art, the December Old Master Part I auction will include a rich array of masterworks. Leading the sale is a striking picture of an Andalusian stallion by Anthony van Dyck, constituting the artist’s first independent grand-scale depiction of a horse. The canvas, painted with extraordinary fluency and vigour, provides a thrilling demonstration of the young artist’s virtuoso handling of paint and bravura technique, with an oil sketch of a landscape on the unprimed reverse — discovered after removal of the relining canvas — which, remarkably, stands as the artist’s only surviving oil landscape study. A masterpiece by Giambattista Tiepolo of the Guilty Punchinello is a rare example of the artist working with the Polichinelle theme in oils, which Giambattista largely treated in drawing. A remarkable Sermon of Saint John the Baptist by Pieter Brueghel the Younger shows one of his most skilfully detailed treatments of the composition created by his father Pieter Bruegel the Elder, which last appeared at auction in 1855, when it was acquired by ancestors of the present owners. The sale includes many other works of exceptional quality and rarity.