"The Lock" by British Romantic painter John Constable on Tuesday sold for £22.4 million ($35.2 million) at a London sale, smashing the world record price at auction for the artist. The 56 x 47 inch (142.2 x 120.7 cm) oil on canvas, which depicts rural life in Suffolk, east England, went under the hammer at Christie's Old Master and British Paintings Evening Sale. The 1824 masterpiece was brought to auction by Baroness Carmen Thyssen-Bornemisza, who admitted it had been "very painful" to let go of the painting, but had no choice as she had "no liquidity". It is one of six paintings from the artist's most celebrated series of large scale works -- The Stour Series -- which also includes "The Hay Wain", now in London's National Gallery. It was the last of the series to remain in private hands, although has recently been hung in Madrid's Bornemisza Museum. Museum trustee Norman Rosenthal criticised the sale, saying it "represents a moral shame on the part of all those concerned." Francesca Von Habsburg, Thyssen-Bornemisza's stepdaughter and another museum board member, also slammed the sale. "The baroness has shown absolutely no respect for my father and is simply putting her own financial needs above everything else," she told The Mail on Sunday. The Stour Series is widely admired for its rich use of colours and expressive brushstrokes. The "Hay Wain" is widely acknowledged to have influenced the early Impressionists after it was shown at the Paris Salon.