Observations: The poster boy for Hollywood's star gangsters

A man in his early fifties is dressed in black tie. He is lit from above, which throws his features into an intimidating scowl. The picture is completed – rather incongruously – by a young cat in his arms.

As images from movie history go, they don't get more memorable than this shot of Marlon Brando as the Godfather. The 1972 movie made a star of the up-and-coming Al Pacino and cemented Brando's position at the top of his game. But the fact that their faces became so well known to worldwide audiences is down to the talents of a lesser-known character

Steve Schapiro, the principal photographer hired to produce promotional images for the film, is exhibiting a selection of previously unseen photographs at Hamiltons Gallery in London. In his career as a photojournalist and film and portrait photographer, Schapiro has captured shots of everyone from Martin Luther King to JFK. In Hollywood, he's worked on more than 200 films, his most famous projects being posters for blockbusters such as Midnight Cowboy, Taxi Driver and Parenthood, as well as The Godfather.

"As it happens, the images I took caught on," he now explains. "Especially Brando with his cat. There were all these animals running around the studio, and one day [Francis Ford] Coppola just threw one on to Brando's lap. In the film, it turned into an epiphany moment for the character, and in effect became the film's logo. Another image, of someone whispering into Don Corleone's ear, has been used in an enormous number of variations. Such pictures instantly give the observer an idea of who this character is and the power he wielded."

Schapiro's role involved being as unobtrusive as possible while the actors worked. As such, very little of what he produced was posed for.

"Brando was a total delight," he continues. "He particularly loved working with the kids in the film's wedding scenes. He had a great repartee with the little girls and the bridesmaids. The mood was very relaxed, there was a lot of kidding around. It is strange that it worked out so well, because Francis really had to fight for Brando's casting, as the studio had other ideas. Brando was considered difficult, and he ended up larking around."

Steve Schapiro's 'The Godfather', Hamiltons Gallery, London W1 (020-7499 9494), 25 February to 28 March