THE raid on the ''Pink Palace'' that is Drumlanrig Castle exploited a fundamental difficulty facing Britain's land-owning class.

To help meet the costs of maintaining their property and priceless artworks, many choose to sign up to the government's ''in lieu'' scheme which grants an exemption from inheritance tax.

Owners can bequeath their property to the National Trust and still continue to live in a house and enjoy their collections. To qualify, though, the works must be on public show for much of the year - a condition which makes security an obvious problem.

Indeed, in an interview three years ago, the Duke of Buccleuch made it clear how important that was, saying: ''They (his art collection) are on display in the parts of Drumlanrig which are open to the public. They're not hidden away. The paintings are part of the attraction of Drumlanrig and will be here after I drop off the perch.''

Yesterday's thieves simply marched in the front door of the pink sandstone castle, overpowered a female guide, and walked out with the Madonna with the Yarnwinder, apparently paying little heed to the CCTV cameras.

Asked about security, the duke's son, the Earl of Dalkeith, 49, said last night: ''You have to remember this is a house that is open to the public. We welcome tourist visitors here. It plays an important part in the local economy and we want that to go on being possible and for people to see great works of art here.

''How you balance that with the need for security and for this type of smash-and-grab raid it's very difficult to know.''

The earl added: ''We are just shocked and so dismayed. This is a treasure that has been in my family for over 250 years. It is the most wonderful work of art by one of the greatest painters in the world.

''It is a work of such peace and beauty. The thought of it being torn away from Drumlanrig like this is very, very sad indeed. It has been enjoyed not just by us, but by tens of thousands of people.

''We are just keeping our fingers crossed and hoping that the police are successful in recovering it. I believe it will be back.''

The castle has now been shut, ahead of this weekend's scheduled closing. Security measures are also expected to be reviewed at the host of other ancient houses around the UK which double as minor art galleries and museums.

Sarah Jackson, the historic claims director of the Art Theft Register, which has run a data base of international art thefts for a decade, said those involved in the theft at Drumlanrig may be the same gang that has recently targeted houses in England and Ireland.

Earlier this year, a gang stole items worth ''hundreds and thousands of pounds'' from Waddesdon Manor, home of the Rothschild collection in Buckingshire. This followed the theft of (pounds) 30m worth of paintings, including two works by Rubens, from Russborough House in County Wicklow, Ireland.

Ms Jackson said: ''There have quite a number of robberies recently, a few in the last few months, and this is quite likely to be part of a pattern, a connection is definitely possible.''

Sir Timothy Clifford, director general of the National Galleries of Scotland, who is on holiday in Italy, told The Herald: ''This is appalling news and I wonder if this is the same arts gang that has been operating elsewhere.

''I know this painting very well. It is worth a lot of money on the open market, and it was on the galleries' shopping list if it ever became available.''

Richard Demarco, the Edinburgh gallery owner, said: ''Its theft is one of the worst crimes in the history of art in Scotland. There was no finer setting for such a masterpiece than Drumlanrig.

''The fact that someone such as the Duke of Buccleuch had the foresight to display it was remarkable. It helped to show that Scotland was a shining light in culture and at the forefront of art appreciation.

''The real horror story here is that whoever buys it can never display it anywhere but in a locked dungeon. The buyer will be someone I loathe - an utterly selfish person and an enemy of Scotland.''

Aside from the experts, locals queried the security arrangements at Drumlanrig. In Carronbridge, a village near the estate, Rob Clarke, 80, who worked on the estate for six decades, said: ''I was shocked to hear the painting had been stolen. Then I immediately thought the security can't be as good as it should be.''

And at the Buccleuch and Queensberry Hotel, in Thorniehill, locals were just as bemused. One customer said: ''Everyone is saying it is a wonder it has never happened before. There have been questions over the security at the castle for years.''

famous missing works

Rembrandt's Jacob III de Gheyn

Stolen and recovered four times from Dulwich Picture Gallery, London

Rembrandt's Storm on the Sea of Galilee

Removed from a museum in Boston in 1990. Worth (pounds) 30m

Cezanne's Auvers sur Oise

Taken from Ashmolean Museum, Oxford. Worth (pounds) 30m

Vermeer's Guitar Player

Taken in 1974 by IRA sympathisers. Found in a churchyard