FEW things are more likely to galvanise public opinion about art than the threat of some work being permanently lost to the area.

The scorn which inevitably greets any new piece of public sculpture, Claes Oldenburg's Bottle of Notes in Middlesbrough, for example, usually gives way over time to a kind of collective pride in possession, so that any suggestion that it might be moved elsewhere will be met with as much uproar as greeted its arrival.

Unlike highly visible public sculpture, however, Auckland Castle's remarkable set of 17th century Spanish paintings - now headed towards a for sale notice - were something of a well-kept secret.

The announcement that they were to be sold by the Church Commissioners for anything up to £20m was, for many in the region, the first they knew of them.

Opinion about whether the county should endeavour to hang on to the pictures is divided, though most people, if asked, would probably be hard put to decide, knowing too little about them. But there is clearly a desire to learn.

Last week's talk on the Zurbarn paintings by Mrs Elizabeth Conran, former curator of the Bowes museum, was a sell-out, with demand for tickets outstripping space in the Auckland Castle room where they hang - and this was her second lecture on the subject.

She believes it would be "an act of vandalism" if the collection of 13 pictures depicting Jacob and each of his 12 sons were split up as a result of going on the open market. The pictures - except for one which is a copy - have been together for 350 years, and in County Durham for about 250 years.

As former curator at the Bowes in Barnard Castle, she is aware that, outside of the National Gallery, the region boasts the largest collection of Spanish painting in Britain. In her talk, she described this as something of a specialism in County Durham.

As well as the Bowes and Auckland Castle, there were works at Ushaw college, she said, and the famous Rokeby Venus by Velasquez, though only a copy of the latter remains here - the original drew huge crowds when it was returned and shown at the Bowes a couple of years ago.

Mrs Conran said County Durham had already lost a considerable number of paintings as owners of stately homes moved away, taking their collections with them. "The sale of the Zurbar£ns could reduce local collections yet further," she said.

The pictures, bought by a former Bishop of Durham in 1756, were painted in the 1640s, probably for the then new South American market - tradition has it that they were booty, captured in a battle at sea between the English and Spanish. They were first sold in London in 1726.

Francisco de Zurbar£n was a court painter to Philip IV of Spain, admired for his dramatic lighting effects, realistic figures - Jacob and his sons are all about 8ft high - and excellent depiction of materials and still life objects.

In the 1650s, after enjoying royal patronage and fulfilling a huge number of commissions, his fortunes floundered, literally though losing money when English battle ships destroyed Spanish fleets, and because of changes in public taste and the increasing popularity of Murillo. He died in poverty in 1664.

The Prado museum in Madrid is said to be interested in the sale. Some, however, would prefer them to stay them to stay this country, at the Bowes museum, though that would depend on national funding and, possibly, public subscription.

Pru Farrier