Caffell, who curated "Into the Light" with the painter and printer Adam Lowe, recognises that the picture may seem atypical of McCartney. "It's certainly unusual," he says, "in that it shows her taste for the surreal, but it also pinpoints many of the qualities which made Linda so special. She had no time for the kind of drawn-out, heavily stylised work which is dead before it's even been processed. Linda shot from the hip - something grabbed her, and she grabbed it." The dolls were not hung on the tree by McCartney but by an artist friend who wanted to create an impromptu open-air sculpture. If there is a correspondence with the poupee photographs of the surrealist Hans Bellmer, Caffell doubts that this was intentional. "I'm sure Linda wouldn't dismiss the connection after the fact, but her eye was too quick to concern itself with interpretation at the moment of shooting. She truly had, to use that lovely phrase, `a hunger in the eye', and she fed it constantly. That's what I feel most in this image - Linda's sense of immediacy."
"Into the Light", which features work by more than 100 artists, including Eve Arnold, Anish Kapoor, Terry Frost and Catherine Yass, focuses exclusively on light-based printing techniques: photogravure, screenprint, permaprint and the platinum palladian print which is Caffell's speciality at his Cotswolds-based 31 Studio. "None of the work in the show was created in a darkroom," says Caffell. "My platinums are essentially very large contact- prints made by placing a negative over specially treated paper and exposing it to ultraviolet light. The process dates back to the 19th century but almost became a lost art as the materials are very expensive." The great Alfred Stieglitz, Caffell remarks, described platinum as "the prince of photographic materials", and Caffell himself is highly selective about the images he agrees to print. "I printed platinums for Linda for about 10 years, and the tonal range of her work lent itself beautifully to the process." It might seem ironic that Caffell should enter his "light studio" to transform an essentially whimsical image into something dark and ominous. "Linda did that," he insists. "Platinum can only deepen something which is already there. I might like to think of myself as a bit of an alchemist, but I know that the key to the philosopher's stone lies in the eye of a Linda McCartney."
`Into the Light' is at the Royal Photographic Society, Bath (01225 462841) until 6 JuneReuse content