The German photographer goes to great lengths to ensure he gets the best pictures possible during a shoot. He can vividly remember the time Kate burst into tears because she was so cold, having spent three days sitting atop a horse in a summer dress during the lashing rain.
"You know how it goes [in fashion], you have to photograph spring/summer clothes in the autumn/winter and then the autumn/winter clothes in the stupid spring," he told guardian.co.uk.
"She sits on this horse freezing, and that's when she cries – and that's when I said, 'We've got to f**king do this picture! Please, let's do it!’ No [I didn't feel bad]. That's actually the f**king job of the model, and it's not so out of the question. I photographed myself sh**ting in the snow – that was a lot more uncomfortable. But I wanted to see what it feels like to be photographed like this and how much you can stand. And what other people complain about is nothing."
Juergen insists his "moral ground is very much intact" and he is always careful to make his subjects feel comfortable during shoots.
He famously took some naked pictures of Dame Vivienne Westwood when she was 68, and it was actually Juergen who struggled on set. He was worried about asking her to disrobe, so she had to take charge.
"We made [the portrait] in her house, then I chose that couch, and then I got nervous and kept saying, 'Can I have another cup of tea? Can we talk a bit more?' And she said, 'Well are we going to do this or not?' 'OK, we'll do it. On that couch please.' And she took off her clothes and then she started to sit down like that [opens his legs] and I just thought, 'F**k! Woah, f**k, I can't believe this! This is actually so right.’"