The artist looked at him blankly, and said he'd never done such a sculpture in a private home.
The works, which he trailed on his Instagram account last night, include one piece which somewhat resembles Rodin's sculpture The Thinker, with the figure's hand gone from thoughtfully supporting his face to covering it in despair – or perhaps Niobe, the classical figure weeping for the loss of her children.
One piece, a vast six-foot high sculpture made from steel by Conrad Shawcross, dominates the RA courtyard, while a specially commissioned work by Turner-nominated Jim Lambie sees the gallery's central staircase transformed into a multi-coloured artwork.
A stash of bronze set aside for Da Vinci's sculpture was needed instead to cast cannon.
It has been nearly 50 years since there has been a full retrospective of Barbara Hepworth's sculpture and drawings in London.
If that were the case then the six pieces of sculpture here look a little like a short biography in wood and stone.
The larger, more traditional high-ceilinged "white cube" space in the rear has accommodated a ghostly slide projector installation from English artist Claire Harvey's "life in black and white" miniature world, plus more conventional sculpture and painting exhibitions from established artists such as Folkert de Jong and Sven Kroner.
Through the window, in the courtyard, you could make out the back of Jeff Koons' huge, Edward Scissorhands-style plant sculpture, Puppy.
The festival will alsofeature a sinister sound sculpture by Janek Schaefer, who lived as a child on the outskirts of Milton Keynes.
The evening, which includes the world premiere of LamenTate, a composition by Estonian composer Arvo Part, also inspired by Marsyas, was originally planned last summer as Kapoor completed his huge sculpture, but has been shaped against the gathering clouds of war.
The highlights are Fujiko Nakaya's meditative fog sculpture, which operates between 12pm and 2pm daily, and James Turrell's hypnotic Within Without, which invites you to lie down inside a viewing chamber and watch the sky through a hole in the roof.
