For 40 years, the prolific Mario Testino has been photographing the celebrity crème de le crème – think Brad Pitt, Claudia Schiffer, Scarlett Johansson et al – with his vivacious portraits gracing high class covers and gallery walls alike. As one of the busiest and most in demand lensman today, he’s been tapped by the royals, gifting the public with portraits first of Princess Diana and later William and Kate, elsewhere known for his iconic model Towel Series.

While the output of Testino’s image is well known to fans, most are perhaps less privy to the influences shaping his work; since he started collecting photography in the 1980s, his personal collection has grown to include over 300 works, amongst them a prized portrait of the actress Vivian Leigh by surrealist Angus McBean, as well as pieces by Wolfgang Tillmans, Vanessa Beecroft and Martin Parr.

Now, playing host to an exhibition, two auctions and an online sale of the photographs that have shaped and informed Testino’s creative vision, this September sees auction house Sotheby’s offer the opportunity to get inside the mind of the legendary photographer. “I always wanted to collect things that weren’t like me,” he offers, “I’ve always been excited by everything that makes me look at something differently.”

The added bonus? The whole shebang will benefit Testino’s philanthropic mission, with money made going to Museo MATE, established in 2012 to promote Peruvian art and culture. Get involved from 1st September.