THE INFALLIBLE TA; STE OF THE POPE

IN NEW YORK on Wednesday, Christie's is selling the collection of one of the greatest connoisseurs Britain has produced this century - the late Sir John Pope-Hennessy, known by his friends and enemies alike as "the Pope". It comprises Old Master paintings and drawings, furniture and Renaissance bronzes, all of which he lived with and loved.

Sir John knew more about art in his teens than most people ever know, and he developed something close to papal infallibility as an adult. His pronouncements on works, which could be delivered with withering scorn, really mattered - attributors trembled, attributions tumbled. His talents earned him the directorship of the Victoria and Albert Museum, then the British Museum and a knighthood. At the age of 64, he kicked the British dust from his feet to become chairman of the department of European paintings at the Metropolitan Museum in New York - where he was lionised by the culture-vulture millionairesses of Park Avenue.

The description he gives in his autobiography, Learning to Look, of touring the Metropolitan European painting galleries in 1976, the year he took over, underlines the assumption of superior knowledge that made him loved, feared and hated: "I found to my concern that they were among the most unattractive, unregenerate galleries in the whole museum. The pictures were abominably hung, some of them had in the past been grossly overcleaned, some of them were very dirty, some were well, some badly framed, and some of them were not what they were supposed to be." He blamed the situation on his predecessor, Theodore Rousseau, who "was agreeable and had good manners, and was a personal friend of many of the trustees. But he had a defective sense of quality, he did not believe in knowledge, and he was a poor administrator."

His own works of art illustrate the side of Sir John not seen by the public, the man who created a pleasant home in which to entertain his friends, decorated with the kind of pieces he could afford on an art historian's salary. There are no newly discovered masterpieces - he bought those for the museums he ran. There are paintings and furniture inherited from his mother, herself a notable connoisseur, Old Master drawings that he bought for a pound or two in the 1930s before anyone thought of paying thousands for them, Baroque paintings he bought at risible prices in the 1940s and 1950s because they were out of fashion, and Renaissance bronzes he picked up in junk shops for a song because no one else recognised them.

Sir John was never a rich man, though he achieved a certain prosperity in the 1980s after selling Domenichino's Christ Carrying The Cross to the Getty Museum for $750,000 - it had cost him pounds 38 in 1946 - and Annibale Carraci's Vision of St Francis to the National Gallery of Canada for pounds 100,000 - it had cost pounds 28. The sale contains a smattering of more expensive paintings which Sir John Pope-Hennessy bought in New York with the Getty dollars in his pocket.

The heir to the Pope's estate is a young American scholar by the name of Michael Mallon, who acted as a combination of secretary and medical orderly after Sir John retired to Florence in 1986. They met when Mallon introduced himself as a fan after Sir John gave a lecture at the Frick Museum. Shortly afterwards Sir John wangled him an internship at the Metropolitan. Mallon proved popular with the Florentines and is the literary executor of both Sir John and Harold Acton, another famous British resident.

Michael Mallon's affection for his benefactor is reflected in the foreword he has written to Christie's sale catalogue: "Rarely can any man of similar accomplishments have appeared - from the finely chiselled outline of his profile (pronounced pro fel) down to the ever-present gold Tiffany links - exactly as he was expected to appear. Inevitably some people disliked him; no one, however, can have been disappointed by him. The interest of the objects presented here is, therefore, twofold: not only is each one of artistic merit in its own right, but, taken as a group, they reflected the taste, indeed the entire personality, of a towering figure in the world of art history."

Sir John Pope-Hennessy's possessions moved with him, like a shell, from Bloomsbury, to New York, to Florence. Indeed some pieces go back to his childhood - and his attachment to his mother is engagingly reflected in the sale.

Dame Una, who was honoured for her work with prisoners of war during the First World War, was a writer of some distinction. In the early years of the century her great passion was the French Revolution and the lives of women who left their mark on that time, notably Madame de Stael. In de Stael's honour she hung a late 18th-century view of Lake Geneva, "the waters of freedom", over her own desk. She knew a really good painting when she saw one, but her son discovered the name of its painter - an 18th-century Dane called Simon Maglo, whom few people have heard of but who had the talent of a Canaletto.

There are also three imposing Italian cabinets that belonged to his mother; the two 17th-century ones are estimated at $50,000-$70,000 (pounds 30,000-pounds 45,000) and $20,000-$30,000 (pounds 15,000-pounds 20,000), and the 18th-century one at $15,000- $20,000 (pounds 10,000-pounds 15,000). The grandest is made of ebony and has drawers decorated with painted glass panels; according to Sir John, "all the scenes derive from the Old Testament frescoes in the Raphael Loggia of the Vatican save one, which is from the New Testament. In one drawer the scenes are replacements, as the figures in them look like the Pellerin Cezannes..."

Sir John first collected sea shells and butterflies. The shells are still extant. "There are drawers and drawers of them," says Mallon, "and I've got the catalogue of them he wrote when he was six or seven - with his own illustrations." At the age of 13 he decided he was going to be an art historian and, Mallon writes, "set out to acquire not only the requisite working library but a suitable collection of works of art... Operating under the constraints of a schoolboy's budget, his attention was first focused on Old Master drawings, some of which he managed to buy in the late 1920s and early 1930s for as little as one or two pounds."

The early Siennese school was his great love from the start. His first book was devoted to Giovanni di Paolo (1402-1483), the leading Siennese painter of the 15th century. The most remarkable of his schoolboy purchases was a sketch for a stage set by Domenico Beccafumi (1486-1551), another great Siennese artist. It is a town view in Pisa, with the roof of the Baptisery and the Leaning Tower in the distance, in ink, lightly touched with brown and pink wash. It is now estimated at $100,000-$150,000 (pounds 65,000- pounds 100,000).

The devotion to Siena lasted the whole of Sir John Pope-Hennessy's life. Flush with cash after selling his Domenichino to the Getty - and with a gap on his walls - he bought a 6ft, gold ground Assumption of the Virgin by Pietro de Franceschi degli Orioli (1458-96) from Colnaghi's in New York. This is by a lesser name and comes in a rather over-cleaned condition, but it is still expected to sell for $80,000-$120,000 (pounds 50,000-pounds 80,000).

Last but not least are the Renaissance bronzes. As keeper of Architecture and Sculpture at the V&A from 1954 to 1966, and as director from 1967 to 1973, he bought every distinguished sculpture he could lay his hands on for the museum - incomparably improving its collection. He only bought for himself things the museum would not want - duplicates or small bronzes, plaquettes and medals. This is a field riven with problems - it is so easy to cast a new bronze from an old one - but a purchaser at this sale will know he is buying pieces that passed muster with the century's greatest connoisseur. An oil lamp supported by griffins' masks and lion paw feet, attributed by Sir John to Severo da Ravenna and dated c1525, is estimated at $30,000-$40,000 (pounds 20,000-pounds 25,000); an exquisite miniature self-portrait by Giambologna c1599 at $80,000-$100,000 (pounds 50,000-pounds 65,000).

This won't be a hugely expensive sale, since Old Masters are relatively out of fashion - some of the 16th-century bronze plaquettes are estimated at only $300-$400 (pounds 200-pounds 250). Christie's is holding the sale in New York in the hope that the ladies of Park Avenue will fight to own a memento of the Pope. !