The New York auction has boosted the fortunes of natural history books, those big, sumptuously illustrated, usually hand-coloured volumes of birds and flowers that have been the pride of gentlemen's libraries from the 16th Century to this day. They have already acquired an international appeal, transcending language.
In this country in the past year, auction prices for such books have risen 10 to 20 per cent, after edging up for a decade. Prices respond to surges in the housing market: rich old couples who judge it a good time to sell their echoing manse and move to a cottage often simultaneously auction their bulky antiquarian books along with the surplus furniture and silver. That stimulates the book market.
Although house prices slumped in the 1990s, prices for natural history books, especially sought-after classics such as John Gould's The Birds of Great Britain (1873), have shown a ratchet-like resilience, creaking upwards by half a per cent or so a year. Now, house prices are surging again. Which is good news for books.
What tips, then, from the ebullient Mr Heald's spending spree? The answer is: a lot and a little. Prices need careful study and condition is crucial - but taste-wise the choices are not difficult. The more beautiful the flowers, the more beautiful the price.
Where's the heat? I asked him. He instanced his purchase in New York, for $189,500, of a sumptuous first edition of Pierre-Joseph Redoute's three-volume folio-sized book of roses, with 169 colour plates, published 1817-1824.
It was estimated $60,000-$80,000. "But," he said, "these were the most beautiful books in the sale - I know I'm safe with them.
"Fashions may change in other fields - for example, short dresses may go in and out of fashion - but a rose is a rose. And Redoute's pictures of roses are the most stunning by any artist in any century. Never mind the more technical, less beautiful drawings - for example, a close-up of the underside of a leaf that some bug finds appetising.
"It is its internationality that gives this market its strength. These botanical books have the same appeal for anybody of any nationality who is capable of walking into a garden, feeling a glow, and saying, `What beautiful roses, what beautiful camelias!'
"If the economy goes off the boil in one country, then beautiful roses such as Redoute's can travel for sale elsewhere."
The lots in New York had last been sold, together, at a famous Sotheby's auction in London in 1987 - so their most recent prices could be gleaned from the price list of a single sale.
You might expect bidders to have used those prices as a marker. But this is obviously not a perfect market. Mr Heald snapped up what he considers to be the most beautiful botanical book by Baron Nikolaus Joseph Jacquin, published 1797-1804, for $145,500, which he estimates is about $5,000 less than it fetched in 1987. Although estimated $80,000-$100,000 this month, he had expected bidding to reach $250,000. "At the risk of gloating," he said, "I must say I couldn't believe my luck."
So don't let the bugs bite - nobody wanted Audouin's Histoire des Insectes Nuisibles a la Vigne of 1842 at Phillips' London auction this month, even at pounds 300-pounds 500 - and go for big, fleshy, colourful flowers.
Here is another market which, like Old Master paintings, has its dry, difficult, academic side, but where the correct instinct in buying for investment is to go for what you like. Moreover, the scholarly specialist book collector is a dying breed. In the ascendant are home-makers who want a beautiful chair, a beautiful painting, a beautiful book. Their taste for beautiful things is leading the market by the nose.
But do study prices. Two annual auction price guides are useful: Book Auction Records, published in Britain by Dawson, and American Book Prices Current (Washington). The former has suffered some delays: 1996 prices will not be published until the end of this year.
Example of price-checking in action: Thomas Hale's Eden, a 1757 gardening book with 60 engraved plates, fetched in uncoloured state pounds 1,955 and pounds 2,530 in 1992 and pounds 4,140 a year ago, at Phillips. Hand-colour at least doubles the value, so someone thought it worth paying pounds 7,820 (against pounds 4,500-pounds 5,500 estimate) for a goodish coloured copy at Phillips this month.
Also at Christie's London on Wednesday (10.30am): two unique, hand-made botanical books, one with original watercolours of ferns, one with specimens of dried seaweed, charming mementoes of Victorian amateur biology: estimates pounds 4,000-pounds 6,000 and pounds 500-pounds 800.
As for Gould's The Birds of Great Britain: pounds 28,000-pounds 32,000 at Christie's, pounds 30,000-pounds 35,000 at Bonhams, Tuesday (10.30am).
If you do not fancy the beautiful, go for the sensational: it will hold its value. Bonhams' Tuesday sale of travel books and maps - biggest for 10 years - offers a very rare 1701 account of Captain Kidd's Murther and Piracy at pounds 900-pounds 1,200. A copy sold in New York in 1995 for $1,700 (pounds 1,030).
Or get the feel for what the London dealer Edmund Pollinger of the London book dealers Henry Sotheran, another fair exhibitor, describes as "hot, sexy titles": Gold, Sport and Coffee Planting in Mysore, 1894, with vignettes of a lion and a coffee plant. Excitement, avarice and a biology lesson, all for pounds 298.
The Antiquarian Book Fair, Grosvenor House, Park Lane, London W1. Preview night Thursday (5pm-9pm) entry pounds 15 including catalogue. Friday (11am-7pm) and Saturday (11am-6pm) entry pounds 5, catalogue pounds 3. Antiquarian Booksellers' Association (0171-439 3118).