The Duke of Sutherland's decision to sell off his collection of old masters will set in motion the biggest fundraising effort in Britain's public gallery sector since the National Gallery set about acquiring The Madonna of the Pinks six years ago. London's National Gallery is involved again, along with the National Galleries of Scotland. They have joined forces in an effort to buy two sublime works by Titian for £100m.

But should the Government get involved and use public money to help acquire the works for the nation? It is a more finely balanced argument than many cheerleaders for the acquisition are prepared to admit. We should not underestimate the inspirational power of great art in national collections. Hundreds of thousands of Britons have been able to enjoy these two paintings for free because they have been on long-term loan to the National Gallery of Scotland. It would be a grave loss indeed if future generations were to be denied that opportunity. And, unlike The Madonna of the Pinks, the Titians in question are indisputably first-rate examples of the artist's work.

Yet there are also counter-arguments to using public money in this way. One is that great art moves around the world much more than ever. "Blockbuster" shows, themed around a single master's work, are greatly in vogue among the world's premier galleries and museums. There is a growing likelihood that great works sold abroad will come back on tour at some stage. There is also something distasteful about a wealthy aristocrat such as the Duke of Sutherland effectively forcing the taxpayer to stump up millions for such works; especially as their market value has often been vastly boosted by their long-term display in public galleries. The duke claims these two works are being offered to the nation for considerably less than he could expect on the open market. But when one considers the tax he would have to pay if he sold them to a private bidder, the offer begins to look rather less generous.

In the end, the outcome of this appeal will depend largely on how much cash can be extracted from the heritage charity sector. The Treasury is not going to stump up all the cash on its own. But ministers might look at whether the tax regime might be further reformed to make it less easy (or desirable) for the holders of these great collections periodically to hold the nation to ransom in the name of art.