Christie’s announced this painting in its Old Master sale in early July:

One of six paintings that make up the artist’s most celebrated series of large scale works which also includes The Hay Wain, now in The National Gallery, London, The Lock is the last to remain in private hands. From the Private Collection of Baroness Carmen Thyssen Bornemisza, it has been sold only once since it was acquired from the artist. When bought at auction in 1990 for £10.8 million, it became the most valuable British painting ever sold at the time – a record it held for 16 years. It is expected to realise £20 million to £25 million on 3 July.