ART / Painter of partridge and ptarmigan: Collectors will gain from a museum's loss when 140 Archibald Thorburn paintings of birds go under the hammer at Sotheby's

MORE THAN 140 paintings by Archibald Thorburn, the greatest bird illustrator of the past 100 years, are to be offered at Sotheby's on 31 March. They come from the Thorburn Museum and Gallery near Liskeard in Cornwall, which can afford to keep only 50 of the pictures.

The sale of the collection, lovingly formed by John Southern over 50 years, will be the best opportunity ever to buy great examples of Thorburn's work, with values estimated at between pounds 200 and pounds 60,000.

The sale dramatically highlights a point often overlooked by museum administrators: a museum and a theme park are not the same thing. They respond to different priorities. The populists at the V&A and the Royal Armouries - who hope to remove the royal collection to Leeds and set up a military theme park - should take note.

The Thorburn Museum is part of Dobwalls Family Adventure Park, the prime attraction of which is Europe's most extensive model railway; it has cafes, restaurants, side shows, and an adventure playground.

Mr Southern began to convert his farm into a tourist attraction in 1970, by building the railway. It is one- eighth real size, and you sit astride the coaches while they meander through Cornish fields remodelled as Colorado, the Rio Grande, and the Wyoming plains. In 1972, he opened the Thorburn Museum in a former cow shed.

Trains and Thorburn had been the passions of his childhood. Born in Manchester in 1931 close to the railway, he became obsessed by trains. On his eighth birthday, he received a book which included a Thorburn illustration of a goldfinch on a thistle head; he bought his first Thorburn watercolour three years later, for pounds 1.

His forest railway, launched in 1970, was an immediate success, carrying 22,000 passengers in 1971. By 1989, it carried around 325,000 passengers annually. Southern ploughed back his profits, constantly extending his many and varied attractions.

In 1986, he remodelled the Thorburn Museum as a series of 'see, hear, touch, feel, smell' cameos of the artist's life and the scenes that inspired his pictures - figures of Thorburn asleep by the fire and at work in his studio, stuffed grouse lurking amidst rocks and heather. There are braille pads for blind visitors, headphones for the deaf, and a simplified commentary by Brian Rix for the mentally handicapped. Wheelchair access is excellent.

Visitors start at Thorburn's dealer's shop in Jermyn St (noises of Edwardian traffic off, cobbled street to suggest history to blind people), and move on to his home near Godalming, his garden, and a Scottish grouse moor (air conditioning simulates wind in your hair and wafts the smell of heather).

The Gallery was opened by the Prince of Wales in 1986, and won Sotheby's award for Britain's Best Fine Art Museum in 1987. Last year, the Department of Trade and Industry helped finance a report on the adventure park's financial problems.

The report suggested that 'the Gallery would benefit from a reduction in the sheer volume of pictures on show, to allow more space for the interpretation of individual pictures and for often requested information on the birds and animals which feature in them'. There, in a nutshell, is the difference between museum and theme park. One shows art, the other teaches and entertains the public.

Mr Southern is facing up to his decision to sell very bravely. 'We're getting some really good prints made,' he said. 'I don't think most of the general public will even notice the difference.'

He is devastated at having to sell the outcome of a lifetime's collecting. He spent 15 months, without success, trying to persuade government and commercial companies to buy the works and loan them back. Sotheby's catalogue contains a plea from Lord Barber of Tewkesbury for buyers to loan their purchases back to the museum.

It is most probable, however, that the watercolours will be snapped up by the sporting - and most especially, the shooting - fraternity. In Thorburn's own lifetime, his clients were mainly keen sportsmen who wanted to hang his wonderfully faithful renderings of grouse, partridges, pheasants, black game and ptarmigan on their walls. The pictures can still be found in the gun rooms and estate offices of noble houses up and down the country.

During the 1980s, as shooting became democratised, Archibald Thorburn's work attracted a lot of new interest. Rearing birds and killing them became a part of corporate entertaining, and the new rich bought or rented shoots from penurious stately home owners.

Nowadays, up and down the country, the new rich as well as the old want to own Thorburn watercolours. An auction price record of pounds 58,000 was set for a Thorburn watercolour at Christie's in 1991.

Archibald Thorburn was born in 1860 in Lasswade, near Edinburgh, the son of a miniaturist who had enjoyed a vogue in the mid-19th century and worked for Queen Victoria. Archibald was taught to draw and paint by his father, and attended an art school in St Johns Wood. Otherwise, he had no formal training.

It was in 1887, when he was 27, that the seal was set on his life's work. Lord Lilford of Northampton had embarked two years before on a seven-volume publication entitled Coloured Figures of the Birds of the British Islands, employing the Dutch artist J G Keulemans, who fell ill. Thorburn took over the job; by the time he had completed 268 plates for Lord Lilford, he had become famous throughout the British Isles.

His originality lay in depicting birds - and occasionally mammals - in their natural environment; the atmospheric detail of his landscapes, faithful to the birds' habitat, are as important to his admirers as the lifelike drawing of the different types of birds themselves.

He tried his hand at oils early on, but soon found that his natural medium was watercolour. From 1880 to 1900 he exhibited ambitious, large- scale watercolours at the Royal Academy Summer Show, but the works were never well hung and he finally gave up on it.

By 1900 he was attracting as many commissions as he could handle; he also continued to make illustrations, writing and publishing his own four- volume book, British Birds, and other lesser works. He could complete a watercolour in a day. Even large exhibition works rarely took him more than a week.

Thorburn married Constance Mudie, whose father ran Mudie's famous lending library, and from then on he was never short of money. With his wife, Thorburn moved from London to a small estate in Surrey in 1902, where he worked with puritan application from dawn to dusk, apart from sketching trips to the north of Scotland. His watercolours were worked up in the studio by combining landscapes, birds and animals sketched from life.

The price estimates for Sotheby's sale have been set below recent market levels, in the hope of ensuring that everything sells. Those who want to buy should expect to pay double the estimate for anything they really like. Specialist dealers assure me that all the watercolours will get snapped up.

(Photographs omitted)