WHO cares who painted The Skating Minister?

Well, I do for one. It is of course Scotland's best known and most loved painting and is used by the National Galleries for its branding, though the original is to be found in a gloomy basement with many other Scottish paintings at the Mound in Edinburgh.

Insensitive as that is, it is nothing compared to the note accompanying it, which suggests it may not be the work of Sir Henry Raeburn, our greatest portrait painter, but an obscure and hitherto uncelebrated Frenchman called Henri-Pierre Danloux. When this claim first surfaced in an article in 2005 by Stephen Lloyd, then a curator at the Scottish National Portrait Gallery (SNPG), it was greeted with hysterical interest and, in general, accepted as fact.

Lloyd's case, which he continues to make in a new book, is that The Skating Minister cannot be by Raeburn because it is stylistically unlike others of his paintings. Moreover, Lloyd now says the absence of lead white under-paint, which supposedly Raeburn habitually used, proves conclusively the Rev Robert Walker, aka The Skating Minister, must have been painted by someone else.

Forgive me, a mere journalist, from stifling a scoff. From the beginning, Lloyd's case was at best circumstantial and at worst plain silly and would, in most courts in the land, be thrown out before wasting a jury's time. By way of evidence he introduced a painting by Danloux in which the pose of one of the figures was similar to that deployed by The Skating Minister. Danloux, it transpired, had spent a while in Edinburgh in the last decade of the 18th century, which coincidence was seized upon by Lloyd to fatten his argument.

It was inevitable, he suggested, that Danloux, who had travelled from France to paint exiled members of the French royal family who had taken sanctuary at Holyrood, would have met the Rev Walker, who was a minister in the Canongate.

And that was just about it. Yet the then director of the National Galleries, Sir Timothy Clifford, who once declared Scottish art to be "inferior", concluded that the attribution of the painting to Raeburn was wrong and that poor Danloux had languished unsung for centuries.

There are various ways you can trace the provenance of a painting. One of the most reliable is by determining a connection between painter and sitter. Despite apparently researching for years, Lloyd has found nothing – not a piece of paper, not a letter or a bill or a diary entry – which associates Danloux with Walker. He has not been able even to confirm they knew each other. Why, then, would Danloux want to paint him if no fee was involved?

In contrast, we know Raeburn and Walker were friends and moved in the same social circles. As regards the painting, Beatrix Scott, the Rev Walker's great-granddaughter, noted Raeburn "always regarded it as his masterpiece". Indeed, on Raeburn's death, he bequeathed it to Walker's widow, Jean.

Though Raeburn connoisseurs concede the painting may be atypical there is no doubt in their minds he was its author. For Duncan Thomson, erstwhile keeper of the SNPG and the world's foremost expert on Raeburn, it is all in the eye of the beholder. The Scot, he insists, describes while the Frenchman imitates.

Yet still the arguments rage and the doubt over the National Galleries' "star" painting is allowed to fester. This is strange because I have found no-one who works there in a curatorial capacity who believes Raeburn did not paint it.

One such is Michael Clarke, director of the National Gallery, who in 2006 said: "If it's by Raeburn, he's painting in a format favoured by Danloux. But if it's by Danloux, he's painting in a style practised by Raeburn. Now, it's more likely to my mind you could paint in another artist's format than paint in a style which is quite different from the rest of your work."

Nothing has changed in the interim, which is sad and shameful, and a reflection, it seems to me, of the inertia and complacency at the heart of our culture. Whatever happened to our much-vaunted national pride?