Saul Leiter, whose beginnings in photography date back to the 1940s, is recognised as a pioneer of colour photography and one of the most important artists working in the post-war period.

MK Gallery in Milton Keynes is playing host to the largest ever UK retrospective of the American photographer’s work in an exhibition named An Unfinished World, which will present over 170 of his photographs and more than 40 of his lesser-known paintings.

After moving from Pittsburgh to New York City in 1946, he quickly became a known figure in the local art scene, forming a group called The New York School of Photography, which included Diane Arbus, Richard Avedon and Robert Frank, among others.

From this period, right up until his death in 2013, Leiter worked feverishly, photographing every single day and eventually amassing a stunning collection of around 15,000 black and white prints, 40,000 colour slides, and over 4,000 paintings.

His lifelong interest in beauty and aestheticism saw him wander the streets of New York City night and day, rain and shine, in search of beautiful scenes. “Photographs are often treated as important moments but really they are fragments and souvenirs of an unfinished world,” Leiter has said of his practice.

In particular, his work from the 1950s and 1960s garnered international acclaim. Though at the time he was mostly known as a fashion photographer, shooting for publications such as Harper’s Bazaar, Elle, and British Vogue, it was his street photography that would become his most enduring contribution to the field.

This was in part because of his embrace of colour photography, which in the early 1960s was not a common feature in the medium’s mainstream. However, Leiter was instinctively drawn to colour, and became one of the first practitioners to truly experiment with this style.

He was known to occasionally use damaged or aged film, and had an eye for atmospheric details like smoke and wet surfaces, all of which allowed him to transform light and colour.

His photographs of New York streets, often shot in a cinematic fashion using a telephoto lens, are renowned for their splashes of red, green and yellow. Throughout his extensive portfolio of work, this way of composing shots remains prominent, and has since become a signifier of his unique approach to photography that celebrates the everyday.

As Leiter himself said, “A photographer’s gift to the viewer is sometimes beauty in the overlooked ordinary.”

An Unfinished World is on show at the MK Gallery, Milton Keynes until June 2; mkgallery.org