By LUKE SALKELD

Last updated at 22:46 06 May 2008

Experts believe this image of a leaf is the world's first photograph

It might be a little out of focus, and need a bit of work on the composition.

But this image of a leaf has been hailed as 'priceless' by experts who believe it could be the world's first photograph.

The red picture had previously been attributed to Henry Fox Talbot, who is credited with taking the world's first photographs in the 1830s.

But some believe this image may have been created in the last years of the 18th century - more than 30 years earlier.

The image - created by laying a leaf on light-sensitive paper and exposing it to the sun - has now been withdrawn from sale by a leading auction house while further investigations are carried out.

Denise Bethell of Sotheby's said: "The possibility of a definitive conclusion regarding this early photogenic drawing is very exciting.

"We were expecting £50-£70,000 for it. If it could be authenticated as the world's oldest photograph, the sky could be the limit."

Fox Talbot (1800-1877) was famed as the first photographer as he was thought to have created the negative - a means of duplicating an image many times over.

The leaf image was last sold as a Talbot original by Sotheby's in 1984 and snapped up by a New York art dealer.

It was due to be sold again on April 7th in New York, but auctioneers asked art historian Dr Larry Schaaf to inspect it ahead of the sale, and were shocked at his suggestion that it wasn't created by Talbot.

Henry Fox Talbot is credited with taking the world's first photographs in the 1830s

Dr Schaaf believes a letter 'W' on the image may stand for Thomas Wedgwood (1771-1805), a member of the china-making family.

Wedgwood was known to have experimented with photography in the 1790s, while living in Bristol, but none of his work was thought to have survived.

Dr Schaaf told Sotheby's: "Well, the first thing I would say is that this was not made by Talbot.

"That was not what they were expecting to hear, to say the least," he added.

The question mark over the picture created great excitement in the art world, and Sotheby's has called off the sale so the photo can be authenticated.

Early photos like the leaf were produced on paper treated with silver nitrate to make it light-sensitive and left in the sun before being developed in a dark room.

As the exposed areas of paper darkened, a pale silhouette was left of the object. Semi-opaque objects like leaves produced great detail, as every tiny vein can be seen.

But too long in the sun darkened the images. This was a problem Wedgwood and the photo pioneers could not fix, and many early examples were destroyed.

The first-ever photograph was thought to be that of a window at Lacock Abbey in Wiltshire produced by Fox Talbot in 1835.

Although surviving letters show Wedgwood advised others on photography as early as the 1790s, none of his experiments have ever been located.

Sotheby's was auctioning the leaf picture as part of Quillan collection, a collection of exhibits from the earliest days of photography to the present.

It was already expected to fetch more than some of the best-known snaps in the collection, such as Richard Avedon's 1957 portrait of Marilyn Monroe (£35 to £50,000).

Until 1984, the leaf was in an album belonging to descendants of Henry Bright (1784-1869), a Bristol MP, arts patron, and friend of Wedgwood.

Five other photogenic drawings from the album were sold in 1984, of which four also bear a 'W'.

Two are now privately-owned, one is in the J Paul Getty Museum and one in the Metropolitan Museum of Art. Both museums will be doing further tests.

Tests can be done to determine the age of the paper and to identify the chemical make-up of any substances used on it.

Dr Schaaf added: "This image of a leaf is extraordinary. It arrests our attention as much today as it had done for at least for a century and a half, and just possibly for more than two centuries.

"Someone could obviously come along and say that these images are all in fact Talbots, but they would be wrong."