LONDON, ENGLAND.- Throughout February and March 2005, Sotheby's will offer a rare and important collection of paintings, sculptures, works on paper, and lithographs by some of the 20th century's leading artists. Amassed over several decades by curator and art historian Jean-Yves Mock, the size and diversity of the collection reflects the range and quality of the exhibitions held during the years he worked at London's renowned Hanover Gallery. It provides a rich visual catalogue of an extraordinary collector and a life dedicated to the arts. Composed of some 240 lots, the collection will be spread over five separate auctions to be held at the beginning of 2005, starting with the Surrealist sale on February 8 and concluding with the Modern British Sale on March 2. The majority of the collection will be offered in a single owner sale at Sotheby's Olympia on February 9.

Oliver Barker, Senior Director of Sotheby's Contemporary Art department in London, said: "We are delighted to be offering this magnificent collection at auction. Largely acquired during the 1960s and 1970s when Jean-Yves Mock worked with Erica Brausen at the Hanover Gallery, many of the paintings and works on paper will be making their first appearance on the open market. We hope the wide eclecticism of the collection will attract a broad cross-section of leading collectors from across the globe keen to capitalise on this remarkable opportunity."

JEAN-YVES MOCK - Jean-Yves Mock (b. 1928) worked at the Hanover Gallery from 1956 until in 1973, when it closed. The gallery was originally founded in 1949 by Erica Brausen, primarily to showcase the work of the then relatively unknown artist, Francis Bacon. It went on to become one of the most important and influential establishments for three generations of 20th-century European artists, holding more than 300 exhibitions in 25 years. It was one of a handful of European galleries devoted to contemporary art at that time, alongside the Berggruen in Paris and Galerie Beyeler in Basel, and handled the sales of many pivotal works of art to prestigious museum collections. Jean-Yves's contribution was instrumental in discovering and promoting some of the 20th century's leading exponents of the avant garde and through his involvement he formed lasting friendships with many artists, as is illustrated by the numerous works dedicated to him in his collection.

When the Hanover Gallery closed in 1973, Jean-Yves was invited by Pontus Hulton, Director of the Musée National de Paris, to join the curatorial team at the Centre Georges Pompidou, Paris. During his distinguished career there he organised the first major retrospectives of Niki de Saint Phalle, Yves Klein and Jean Tinguely and, in 1984, he curated La rime et la raison at the Galerie National du Grand Palais, the only exhibition dedicated to the highly important international collections of the De Menil family. His invaluable contribution to the arts was acknowledged by the French State when he was made a Chevalier de l'ordre des arts et des letters in 1985 and awarded L'Ordre du Merite in 1993.

THE COLLECTION - Works to be offered at the Surrealist sale on February 8 include three pieces by Man Ray (1890-1976), among them the original Pêchage, 1969, illustrated on the front cover of Roland Penrose's influential 1975 monograph on the artist, and three important works by René Magritte (1898-1967). Of particular interest is Le Chef d'œuvre, a gouache executed in 1964, it is one of the finest examples of the artist's work from this important period ever to appear at auction. Included in Magritte's first exhibition at the Hanover Gallery in 1964, this work was a bequest to Jean-Yves Mock from the estate of Erica Brausen, the gallery's owner, and has been seen in public only once since. It is estimated to fetch between £300,000-400,000 (€427,545-570,060). A second Magritte, Le Corps Bleu, painted in 1928, is estimated at £200,000-300,000 (€285,030-427,545) and is an important example of the symbiosis of Surrealist ideas between Magritte and his close friend, the sculptor Jean Arp.

The following day four drawings by Alberto Giacometti (1901-66) will be included in the Impressionist and Modern Works on Paper sale, with estimates ranging from £20,000-80,000 (€28,503-114,012). These include a rare and exquisite self-portrait from circa 1954-5 estimated at £60,000-80,000 (€85,509-114,012).

The Contemporary Evening sale on February 10 will include three masterworks on paper by Andy Warhol (1928-87), Roy Lichtenstein (1923-97) and Yves Klein (1928-62). Acquired by Mock during the early 1960s these rare and exceptional works have not been offered on the open market since and are all fine examples of these artists' work. Warhol's Soupcan, estimated at £120,000-150,000 (€171,018-213,773), was executed in 1962 dramatically presaging his breakthrough Campbell's Soup paintings exhibition at the Ferus Gallery, Los Angeles, later that year. It is arguably the most important and exceptional early drawing by Warhol ever to appear at auction. Also exceptional for its size and outstanding clarity is Lichtenstein's exquisite large pencil drawing Temple of Apollo.. Executed in 1964, it is one of the largest drawings by the artist of its kind still in private hands. It is estimated at £150,000-200,000 (€213,773-285,030). Klein's ANT 23 is one of the finest and most important examples from the iconic Anthropométrie de l'époque bleue series, dating from his much publicised live performance at the Galerie internationale d'art contemporain, Paris. Estimated at £100,000-150,000 (€142,515-213,773), the proceeds from the sale of this work will be donated to the Fondation Claude Pompidou, Paris.

The largest part of Jean-Yves Mock's collection of Contemporary works is made up of an impressive group by the French artist Niki de Saint Phalle (1930-2002), the Swiss sculptor and experimental artist Jean Tinguely (1925-91) and the American sculptor Louise Nevelson (1900-1988). This large group of works, in a wide range of media, will be offered in the single owner sale at Sotheby's Olympia on February 9 together with other fascinating works by artists as diverse as Josef Albers (1888-1976), Serge Poliakoff (1900-69) and Henry Moore (1898-1986).

A unique group of 22 paintings and works on paper by William Scott RA (1913-1989) will be offered in Sotheby's Modern British sale on March 2.