Martin Usborne had a good childhood on the whole, but he has one unhappy memory that persists. Left alone in a car one day, the feeling of helpless abandonment stayed locked within him.

“I don’t know when or where or for how long, possibly at the age of four, perhaps outside Tesco’s, probably for 15 minutes only,” he recalls. “The details don’t matter. The point is that I wondered if anyone would come back. It seems trivial now, but in a child’s mind it is possible to be alone forever. Around the same age I began to feel a deep affinity with animals – in particular their plight at the hands of humans. I remember watching TV and seeing footage of a dog being put in a plastic bag and being kicked. What appalled me most was that the dog could not speak back. Its muteness terrified me.”

Now a well-established professional photographer, he was reminded of these feelings by the recurring sight of dogs locked inside their owners’ vehicles, unable to speak out, and decided to make a project out of it. The result, Mute, on show at The Print Space in London until 09 November, is unsurprisingly dark, but it’s not without humorous touches. “I do think of them as portraits, even though they are of dogs, because the images are focused on their faces and they do seem to be expressing various emotions,” says Usborne. “Some of them look expectant, others resigned, others agitated. Yes, you could say I was anthropomorphising, but then I think that all portraits are about the photographer as well as the person in the photograph. They’re never a simple reflection of the subject’s feelings.”

Initially Usborne hoped to shoot a documentary-style project, but quickly realised it was impractical, so instead he enlisted the help of willing dog owners. He says he usually had to take at least a couple of hundred images on each shoot to capture just one soulful moment, which meant each session took at least three hours, shot on his Canon EOS 5D Mk II.

“The camera is the perfect tool for capturing a sense of silence and longing,” he says. “The shutter freezes the subject forever and two layers of glass are placed between the viewer and the viewed: the glass of the lens, the glass of the picture frame and, in this instance, the glass of the car window further isolates the animal. The dog is truly trapped.”

He found the images worked best if he shot the dogs at night, as it cut down on unwanted reflections, so he took along quite a collection of equipment to each shoot, including a bank of portable lights, batteries and even a smoke machine. “I found myself in some crazy situations,” he laughs. “On one shoot I was with this lady with five huskies outside a council estate at 11 o’clock at night. The only thing that would make them quiet was Sinead O’Connor’s Nothing Compares 2 U – they loved that song – so we had to drive my car up alongside and play it at top volume.”