Feb. 27 (Bloomberg) -- Anthony d'Offay, a retired gallery owner, today made a gift which will add 725 works to British art collections by artists including Andy Warhol and Damien Hirst.

The artworks are valued at about 125 million pounds ($250 million) and will be acquired for 28 million pounds, said an e- mailed release by Tate and National Galleries of Scotland.

The release called it ``one of the largest and most imaginative gifts of art ever made to museums'' in the U.K.

London dealer D'Offay, whose donation also includes pieces by Joseph Beuys, Anselm Kiefer and Gilbert &George, will get 26.5 million pounds, representing the amount that the works originally cost him, while the other 1.5 million pounds is the cost of administering the acquisition.

``A gift of this magnitude will completely transform the opportunity to experience contemporary art in the U.K.,'' Tate Director Nicholas Serota said in the release. ``Anthony d'Offay's imaginative generosity establishes a new dynamic for national collections and is without precedent anywhere in the world.''

The British and Scottish governments each contributed 10 million pounds, with 7 million pounds coming from the National Heritage Memorial Fund and 1 million pounds from the Art Fund.

The D'Offay collection will be known as ``Artist Rooms'' because it has been his practice to arrange the works in a series of galleries, each devoted to a single artist. Until he closed his Mayfair gallery in 2001, D'Offay, 68, had been for more than three decades one of the most important contemporary art dealers in London. He also bought pieces by many of the artists he represented.

Art Passion

``I believe passionately that creative young people need to have available to them the best contemporary art,'' D'Offay said in a telephone interview today. ``If you are a student in Sheffield, Aberdeen or Cardiff you need to be able to see contemporary art. It's not always an easy thing to do to buy art in depth, so we did everything we could with all the help we could get from the artists -- who were incredibly generous.''

Up to now, the Tate had only had one Koons, consisting of basketballs floating in a tank and not representative of his wider output, and the Edinburgh museums had none. The new gift adds 17 pieces to this total, including a marble double sculpture, ``Bourgeois Bust -- Jeff and Ilona'' (1991) representing the artist and his ex-wife Ilona Staller, La Cicciolina, porn star and politician.

The additions will also boost public holdings of work by Hirst, the most prominent younger British artist of the last 15 years. The D'Offay collection has five Hirst works including ``Alone of All the Flock'' (1995), a fleecy white lamb in formaldehyde, which was famously the target of an attack by a vandal armed with ink.

Kiefer, Ruscha

The six works by the German artist Kiefer will more than double the Tate's present array; so too will the 14 by his fellow countryman Gerhard Richter, and the 22 by the Californian Ed Ruscha. Neither of the photographers Diane Arbus and Robert Mapplethorpe were previously represented in the Tate or National Galleries of Scotland. D'Offay has 69 prints by Arbus and 64 by Mapplethorpe.

``We were conscious of what was not represented,'' D'Offay said, ``so there is possibly the best collection of Arbus's work, for example, and the best collection in the world after the Guggenheim of Mapplethorpe. We were thinking all the time of what is in the Tate, what is in Edinburgh, what can be seen outside those cities.

``For the last seven years I've been working with my wife Ann Seymour and Marie-Louise Laband, the director of my gallery for 30 years, on putting together these 50 rooms,'' D'Offay said. ``We felt that these particular artists and these configurations of works would be powerful for young people.''

Most significant of all are the 232 items by Warhol, transforming the British national collection of his work. While the Tate Modern is an architectural monument to modern art, the collection it houses is patchy. This aesthetic transfusion will change that. Now, we begin to understand why Tate Modern needs its extension.

(Martin Gayford is a critic for Bloomberg News. The opinions expressed are his own.)

To contact the writer of this report: Martin Gayford in London at martin@cgayford.freeserve.co.uk.

Last Updated: February 27, 2008 05:30 EST