Catherine's great collection returns to evoke splendour of Walpole's vision

Old Masters that once hung on the walls of 10 Downing Street and were snapped up by Catherine the Great of Russia in 1779 will return to London this month - on loan only.

Students of the lessons of history will find the "Houghton Hall" exhibition a rich seam. It tells how Britain's first prime minister, Sir Robert Walpole, built up one of the country's greatest art collections and how it was sold to pay off debts.

Just as would happen today, the sale was discussed in the Commons and a plea was made to save the paintings for the nation. And just as inevitably Parliament, or the Treasury, was unmoved.

The export of the collection to Russia was described at the time as "one of the most striking instances that can be produced of the decline of the empire of Great Britain".

Of the 181 Old Masters acquired by Catherine, six will be in the exhibition which opens at Kenwood House, Hampstead, north London, on 23 January. Together with other Walpole paintings, sculpture, manuscripts and furniture, they are intended to evoke the splendour of the collection amassed at Houghton Hall, Norfolk.

Walpole transferred the works to Houghton on his fall from power in 1742. The great Palladian mansion had been built to house the collection - saddling his heirs with debts.

When Walpole died in 1747 the collection included 400 pictures and was rivalled only by that of the King. But the cream was lost to Britain when George, Walpole's grandson, sold the paintings in one of the greatest coups in art history. Catherine acted with ruthless determination and for about pounds 40,000 acquired 181 of the finest pictures to stock her new pavilion, the Hermitage. Collecting had become almost state policy for the empress. Informed by her adviser, Baron Friedrich-Melchior Grimm, that the Houghton collection was no longer available, she retorted: "The Walpole pictures are no longer to be had for the simple reason that your humble servant has already got her claws on them, and will no more let them go than a cat would a mouse."

Works by Dutch and Flemish masters and from the French and Italian schools formed the bulk, many of which still enrich the walls of the Hermitage in St Petersburg. Rembrandt, Rubens, Van Dyck, Maratti and Poussin are among them. Three paintings direct from the Hermitage will be on display at Kenwood, including The Holy Family by Nicholas Poussin, and three acquired by Catherine, but then sold by the Soviet Union for hard currency. The latter trio includes an acclaimed portrait by Anthony van Dyck of his patron Lord Wharton, which is now in the National Gallery of Art, Washington.

The six will be shown at Kenwood with works from Houghton, in the private collection of Walpole's descendant, the Marquess of Cholmondley, and other galleries. James Christie, founder of Christie's, valued the 181 paintings at pounds 40,455 though one source records that the empress paid only pounds 36,000.

Whatever the precise figure, it was fairly hefty in 1779 and she had no serious competitor - certainly not the reformist MP, John Wilkes, whose plea to save the pictures and make Britain "a favourite abode of the polite arts" fell on deaf ears.