The emergence of an 11th work from the series is, therefore, something of an
event. But, before Christie’s could offer it for sale, it had to be
authenticated. This was no mean hurdle, considering that even signed and
previously accepted works by Warhol (self-portraits, flower paintings and
Brillo box sculptures) have been rejected by the draconian Andy Warhol
Authentication Board, whose adverse decisions can deflate the value of a
work with an ineradicable stamp without so much as a word of explanation.

Auctions will not sell Warhols without catalogue raisonné numbers or
certificates of authenticity. But, in this case, it seems, the painting was
passed without a hitch. Although not signed, it now has the board’s stamp of
approval – number A102.103 – on the back.

So where has the painting been for so long? Christie’s catalogue will state
only that the painting was bought from one of Warhol’s main dealers, Leo
Castelli, in 1974, and that it is now being sold by an American estate. As
for the price, Christie’s has estimated the painting will fetch between £3
million and £5 million ($4.6 million to $7.5 million).

The timing is good because the Warhol market has been buoyant in the past
year. In the last New York sales in November, 65 Warhols, estimated to fetch
$92.5 million, brought more than $200 million. Only three of the large 1967
self-portraits have ever been at auction. In 1984, one was bought by Charles
Saatchi for £70,000 and has since changed hands twice. Another sold in 1998
to the Swiss dealer Ernst Beyeler for $2.4 million and is now in the Beyeler
Foundation collection, while a third sold in 2004 for $6.95 million.

The other pertinent price is the $6.1 million (£3.7 million) paid by jeweller
Laurence Graff in November 2009 for one of the smaller, 22in self-portraits.
Like the present work, it, too, was a rediscovery. It had been kept in a
closet by Warhol’s former assistant at the Factory, Cathy Naso, for 45
years, was not included in the catalogue raisonné, and had to go through the
authentication process before it could be sold. If Warhol prices could be
measured by the inch, which is not as absurd as it sounds, this latest
rediscovery should, therefore, be worth more than £10 million.

That sets the stage for a fascinating duel next month between Sotheby’s Bacon
and Christie’s Warhol – each iconic in its way and emerging from obscurity
into a market that has bounced back from recession with remarkable panache.