THE debate has raged for just a matter of weeks . . . but some of the world's leading art experts have admitted to the Sunday Herald that they have believed for years that the iconic Scottish painting The Skating Minister was not, in fact, the work of Henry Raeburn, but of the French artist Henri-Pierre Danloux.

The acknowledged international expert on Danloux is so convinced that he plans to include The Skating Minister in an exhibition of the French artist's works that will visit Edinburgh, Paris and London in 2009.

Olivier Meslay, curator and British paintings specialist at the Louvre in Paris, has never spoken out about his belief that Danloux painted the portrait because he believed it would be too politically sensitive.

Instead, the debate was kicked off last month, when Dr Stephen Lloyd, a senior curator at the Scottish National Portrait Gallery, gave a scholarly lecture in Edinburgh, airing his detailed conclusions in public for the first time.

His research will be published in the Burlington art magazine in July, and will also suggest the location was Lochend rather than the commonly accepted Duddingston Loch.

Meslay had planned to raise his suspicions at a conference in Edinburgh last November but chickened out.

"It would be tricky that it is a Frenchman who is about to say - in front of Scots - that this is not by Raeburn, by your Scottish artist, but by a Frenchman, " he told the Sunday Herald yesterday.

Meslay's political sensitivity got the better of him. "I found it embarrassing - it would be like a Scot coming to say that the most beautiful painting by David [the French neoclassical painter and revolutionary] in the Louvre was by Raeburn.

Even if it is true, it is better that a Frenchman says it!

"When it is such a famous painting and a Scottish icon, on bags, magnets, and the name of someone very close to Raeburn. . . it is difficult to challenge. It is accepted more easily that it was revealed by Stephen Lloyd."

Alastair Laing, adviser on paintings and sculpture for The National Trust in London, believes he was the first to suggest to other art historians that The Skating Minister may have been painted by Danloux.

"Certainly, people had treated the picture for some time with doubt, but I had never seen anyone's name associated with it, " he told the Sunday Herald.

It was a Raeburn exhibition in Edinburgh and London in 1997-98 that sparked Laing's doubts. "It was only when I went to the Raeburn exhibition in 1997 that Danloux occurred to me, and I did say it to some people but never did anything about it. It was just a hunch, backed up by my knowledge of the two artists.'' The active figure reminded Laing of a painting by Danloux of Mademoiselle Rosalie Duthe hanging a painting: "He was good at showing a graphic, active figure performing, which is unusual in British and French painting of the era.

"With the skater, you really feel the motion, and Mlle Duthe showed Danloux had that kind of imagination not to portray a classical position, or the accepted norms of genteel behaviour. It is the scale of a number of his works and he was in Edinburgh at the right time to have painted the picture."

Laing's proposal spread to experts around the world, but he did not say anything in public. "It clearly is a little embarrassing, when the architect of the Scottish parliament apparently took the shape of his windows from it - but the truth must out.

"At least [Danloux] is of the Auld Alliance - it would be even worse if it was by an English artist."

Several years ago, Laing's suggestion reached the ears of Meslay, who is compiling the official Catalogue Raisonne of all of Danloux's work, and editing a new edition of his diaries.

"Four years ago, I had never thought about The Skating Minister - it is very difficult to look at such a famous painting and say immediately it is not by Raeburn, " said Meslay.

"But the moment you are told, it is completely obvious. It is like being given a key- and watching the door swing open.'' Dr Colin Bailey, chief curator at The Frick Collection in New York, borrowed the painting for an exhibition several years ago and had the same hunch.

"It is a great painting but like no other Raeburn we knew - but it did look like a genre painter called Henri-Pierre Danloux, who happened to be in Edinburgh for a while, " he said. "I wasn't aware of the national status of the work, and a couple of people have talked about the possibility that it might be by Danloux.

I'm glad Stephen Lloyd has made it more public."

Lloyd said that a flood of e-mails, letters and personal comments have supported his new claim, and thinks that although it is based on circumstantial evidence, written proof from diaries will emerge. He suspects that a Portrait Of The Late Dr Walker by Raeburn - mentioned in a sale of 1896 - is an entirely separate, lost work.

"It is fair to say that this has been thought of for some time, but I did have a few sleepless nights and it will remain a controversial issue, " he said. "It is still a great icon, this dour Calvinist minister skating in a position of great elegance."

But Dr Duncan Thomson, former keeper of the National Portrait Gallery and a Raeburn expert, maintains that it is "absolutely typical Raeburn" and is giving a "rebuttal" lecture at the Weston Link [the building between the National Gallery and the RSA] on April 28. Last week, another Raeburn specialist, Dr David Mackie - who lists The Skating Minister in his PhD catalogue of Raeburn's paintings - stood by his research.

"I have no interest in discussing Raeburn at this time during this period of excessive interest in the artist in Scotland, but what I can offer is that you go to see my complete catalogue of Raeburn's paintings in Edinburgh University Library, " he wrote.