The Saatchi Gallery, she explains, is ideal for displaying models - architectural models, that is. And architects' drawings. That is what the auction will sell. And that, rather than contemporary art, is what Doris Lockhart Saatchi is now busy buying.
Over a dinner catered by the Ivy restaurant, the 55-lot sale will be compered by Janet Street-Porter and Piers Gough, architect of Street-Porter's controversial house in Shoreditch and president of the Architectural Association, the 150-year-old independent school that has produced such cutting-edge names as as Rogers and Hadid, and in aid of which the auction is being held.
Donations to be sold range from a stunning 1947 pencil study by Le Corbusier of sunlit angles on tall buildings, to models by such established architects as Foster and Hopkins and Bankside competition winners Herzog and De Meuron - all items which, according to Lockhart-Saatchi, "would not normally be available at any price". Also on offer: the first publicly sold drawings by bridge-whizz Calatrava and the visionary Soleri.
Calatrava? Soleri? Ever heard of them? Or Ando? Or Moss? You will. At the dinner the talk will not be about whether Charles Saatchi will show up - he seldom attends even his own exhibition openings - but about whether his ex-wife is able to turn architectural artefacts into as big a set of money-spinners as the "School of Goldsmiths" artworks which the Saatchi Collection has so long championed. It's a market that is as yet untapped.
"It's my feeling," says Doris Lockhart-Saatchi, "that people are becoming interested in contemporary architecture in the same way that they became interested in contemporary art 10 years ago." And she's about to launch her Mayfair mews home as the first gallery in the country dedicated to selling architectural works.
It's in that house's Spartan interior that we're now talking. The gang - her three Burmese blue cats, Chico, Spec and Blue - have just had their lunch (chicken thighs spiced with bouquet garni) and are now romping on a plan for her new island home in Massachusetts, overlooking the Atlantic.
The plan is by the British architect David Chipperfield, whose plywood model for another Lockhart-Saatchi home, this time in Italy, is included in the sale. Its owner has been tracing the floor plan, overlaying it with changes and additions - a screen wall, for example, in the bedroom, in keeping with her ideal of privacy without closed doors.
"For years," says this 57-year-old Memphis-born, Sorbonne-schooled daughter of a Russian emigree mother and an American journalist father, "we [presumably meaning the British] have produced some of the best architects in the world. I'm thinking of Foster, Rogers, Hadid. But until recently they had built very little in Britain. Even now, you have to go to Switzerland or Germany to see Hadid's work."
She removes a cat from the table and drapes it over her shoulders. Bouncing about the room, her short, rounded figure encased in black jumper and slacks, she speaks non-stop.
When she and Charles came together in 1970, they embarked on an art-buying spree that, for him, has never ended. Critics who did not share the Saatchi taste in contemporary art demonised Doris. But it is five years since she herself bought a work of contemporary art - years spent travelling abroad, interviewing architects for her forthcoming book Architects at Home.
The contemporary art on her walls - a cluster of outstretched plaster- filled yellow kitchen gloves holding bingo balls by Craig Wood, an axe handle with taped end by Sarah Seager - will soon make way for architectural drawings. "Four, perhaps, on the wall over there," she gestures, "and the table here will hold maybe two models. This space really lends itself to architecture.
"I'm not necessarily seeking to present unknown architects to the world. These people are successful enough not to need anybody's help. What I look forward to is displaying whole suites of drawings that go from a conceptual sketch to something that you could build tomorrow. It's an amazing process. Architects have to work under all kinds of constraints - budget, site size, health and safety regulations. A series of drawings can show how an architect has put it all together. It may not be intended to be beautiful, but it is."
But who will buy it? She wants museums, architectural institutions and serious collectors to buy entire suites of drawings. The gallery will be open by appointment only. Browsers in search of single-drawing "souvenirs" will not be encouraged.
Can she pull it off? A couple of pointers in her artistic track record suggest that she might. In 1981, her review of the RA's exhibition The New Spirit in Painting in the RA yearbook was the only one to hail it as a landmark show. The show's theme was that, after the spareness of conceptual and minimalist art, expressionistic painterliness was back. Newspaper art critics panned the exhibition. "But I thought it was wonderful: it took five or six years for the lessons of that show to sink in."
And, in 1970, when she and Charles began collecting together (they married in 1973), he had never bought any art. Look at him today.
The jibe, then as now, was that Doris had the eye and Charles the wallet. "I had my own money," she retorts, "and he had both an eye and a quick mind. If you really want to know, I think the Saatchi Collection came about because the two of us happened to collide at the time we did. We had an uncanny sense of agreement about things. We would walk into a gallery, circle the room, meet up where we had started and discover that we agreed on whether the artist was interesting and even which were the best works. It was thrilling."
By the time rotting cows' heads and pickled sharks came on the scene, the Saatchis had separated. But not before their uncanny fusion of artistic taste had led them separately to the studios of the exciting new wave of young British talent: Langlands and Bell, for example, who base their art on architectural plans and models and, of course, Damien Hirst, star of the Goldsmiths' Class of 88. Although living apart, they found themselves treading the same path as individual collectors that they had beaten together. Hirst found them popping in and out of his studio one after the other, like the to-and-fro couple in a weather house.
"It was so amusing. Whenever I visited Damien or one of the new young galleries that were springing up in out-of-the-way places such as Peckham or Docklands, I was told that Charles had just left, or heard later that his visit had followed mine. We were discovering the same art with the same excitement within days, or even hours, of one another."
Doris gave Hirst a contribution towards the cost of making his first big piece - a huge glass case containing a rotting cow's head and maggots that hatched as bluebottles before meeting their doom in neon insect-zappers. Charles then stepped in and paid for the whole thing. Hirst in turn offered Doris The Only Way Is Up, a work consisting of pills stuck on board, doused in some inflammable liquid and ignited, sending up oily black stains. "Damien says they're uppers. I wouldn't know."
The work hangs on the wall of her spacious sitting-room, opposite a pale pink diptych by Gary Hume, Dolphin Painting V, and overlooking a Mies Van Der Rohe day bed. On the table, three grapefruit-sized balls covered with brown studs that I took to be a David Mach match-heads piece. "They're clove balls from Clifton Nurseries," says Lockhart-Saatchi, diplomatically: "they scent the room." On one wall is a row of four bright brass chains suspended from screws. A minimalist work? "They're the hanging chains for a triptych by Stephen Buckley that has gone off to a show."
The controversy that Doris has sometimes aroused bothers her not one jot. "I didn't give a toss about the reaction," she says, when I remind her of her much-quoted remark, at the 1992 Labour election rally, that she was not a Bollinger Bolshevik but a Dom Perignon Democrat. (At the time, Charles was the Tories' campaign adman and she had been awarded a substantial divorce settlement.) Even a memorably venomous article in Modern Painters, which wilfully misquoted her praise of the RA's New Spirit in Painting exhibition and lamented her malign influence over Charles, passed over her head. "It was hilarious," she says.
"Charles and I got used to having our taste in art sniped at. It was considered weird. I was the brash American and he was the secretive manipulator, plotting to use art to take over the world. It was not until later that critics decided that our collection was something special."
Even today, she is occasionally held responsible for Charles's art-buying - and selling. He was roundly criticised for profit-taking on his Schnabels - nine of which had grown in value after being exhibited at the Tate - and more so for dumping on to the auctioneers' block work by young artists whose fragile reputations depended upon having been bought in bulk by him in the first place.
When, in 1993, nine artworks by raw young artists from Doris's own collection were spotted at a Christie's sale by a sharp-eyed Art Monthly correspondent, she came in for more stick.
"I don't see any problem with selling if your eye has changed," she retorts: "people's sensibilities do alter. I collect because I'm a born collector. Collectors feel compelled to do it. We may all be as neurotic as hell, but there's no plot."
We resume thumbing through her auction catalogue. "That Corbusier drawing," she says, "I'd love to have that."
"You'd better bid, then," I suggest.
"Hmm, it'll go for quite a sum."
"How much, do you reckon?"
"It depends if there's a market here. People really should be drawn to it. After all, cities are here to stay. People are beginning to realise that we've got to make cities work. And that architects can make life better or worse for us. It really does matter."
Architectural Association 150 Campaign Auction: 7.30pm 27 May, Saatchi Gallery, 98a Boundary Road, London NW8. Tickets pounds 150 from 0171-916 8147Reuse content