Aristocrats at war over £22m sale of Constable painting

John Constable's The Lock was sent for auction by Baroness Carmen Thyssen-Bornemisza (AP)

The sale of one of John Constable's finest works, an idyllic depiction of rural Suffolk, has provoked a bitter dispute in one of Europe's most flamboyant aristocratic families.

The Lock, painted in 1824, was sent for auction by Spanish socialite Baroness Carmen Thyssen-Bornemisza, who says she is a victim of Spain's economic crisis and must sell the work to raise funds. The baroness, a former Miss Spain, owns four luxury villas and an art collection which includes eight Gauguins and a Picasso. But her decision has led to a family rift and the resignation of one of the trustees of her museum in Madrid.

Constable's masterpiece went under the hammer at Christie's in London last night and was sold for £22.4m to an unknown buyer – a record amount for the artist and among the top five prices ever paid for an Old Master in Britain. The Lock is one of six large-scale canvases of the River Stour, also including The Hay Wain, that Constable exhibited to acclaim at the Royal Academy in London between 1819 and 1825. It was bought by the baroness's late husband, Baron Hans Heinrich Thyssen-Bornemisza, in 1990 for £10.8m, then a record for a British painting.

But its sale has infuriated the baroness's step-daughter, Francesca Von Habsburg, who said her late father, a renowned collector, would never have agreed to it. "The proposed sale is entirely self-serving and should not go ahead. [The baroness] likes to pretend she is a typical Spanish citizen who is struggling just like everyone else, but that could not be further from the truth," she added.

The sale prompted Sir Norman Rosenthal, a former Royal Academy exhibitions director, to quit as trustee of the baroness's museum. He said it was "morally shameful" and accused the baroness, 69, of having no understanding of art history or appreciation.

So does buying a Constable make financial sense? The Hay Wain, housed in the National Gallery, is unlikely ever to be placed on the market, so buying The Lock was a unique opportunity for collectors.

But the £10.8m paid for it in 1990 was seen as hugely disappointing, and well below the anticipated £15m. That it fetched £22.4m last night might sound a lot but, given inflation, interest and the costs of owning a masterpiece, experts believe it would have to be sold for £60m to outperform other investments the owners could have made over 22 years.