Manolo Blahnik has always beat to the sound of his own drum. As anyone who works in fashion will attest, he is one of the industry's best-loved most influential designers and also the greatest shoe-maker of the 20th Century. He has an incredible interest in the world and people, a pre-requisite of any truly brilliant designer, and a cultural literacy that has never waned over his 74 years.

He has never paid a blind bit of notice to trends or fashion – he makes beautifully feminine, comfortable shoes characterised by their elegant shape and delicate embroidery. With all this in mind, it comes as no surprise that he's the subject of a new documentary entitled Manolo: The Boy Who Makes Shoes For Lizards – a reference to his original clientele caught in his mother's back garden in the Canary Islands.

"To tell you the truth, I haven't thought about it," he says when asked what he hopes people will learn from the documentary. "I couldn't care less about what people think about me. When you reach a certain age, you don't give a damn. I'm an old boy now. That's the truth. Reputation, fame and being well-known, those things never entered my head. As long as I don't kill people, then I'm happy with anything."

Although he says he doesn't care what people think, he does very much care about how he looks – and, if truth to be told, he's not thrilled with how he comes across in the documentary, which was created by Michael Roberts.

"I would have loved not to have been pictured in it," he says. "I broke my diaphragm after I fell over in my house, and the only way of treating it was with a course of cortisone and, well, I became huge. Each ankle was like a column. The neck was like somebody's whole face.

"I wanted to be photographed just from the back, which Robert said he'd do, but it is what it is. I'm not happy with seeing myself on the screen. It makes me vomit. I don't want to see my stupid face again," he says dramatically before laughing loudly.

Whether he wants to see his face again or not, lots of other people do. Style icons and fashion's most zeitgeist brands want to work with him. Case in point is his collaboration with Rihanna, which has resulted in three collections.

"I adore her movement," he says. "Her every movement encapsulates all her Bayan culture and that's what captivated me about her. That and her beautiful eyes. But you know, I can't work with everybody. We've done the last collection now and I said to her, 'goodbye my dear darling. That's it. I'm tired.' For the time being, it's over. I can't cope with it all. I'm not a spring baby anymore."

He says this but you just know he won't book a holiday, wear a pair of flip-flops (which, incidentally, he's not adverse to) and spend a week doing nothing. "I'm very impatient and I'm not relaxed at all," he says. "In fact, I'm very nervous. I always have been and I always will."

His nervous disposition aside, Blahnik is too curious about the world to sit still for long; he's too excited by new ideas and originality. Last season, he was approached by Vetements to work together and couldn't turn it down. Brilliantly for a label known for its extreme proportions, they asked Blahnik to dial down his ideas.

"Last year, they were doing very exciting things," he says. "I loved what they were doing at Balenciaga - they brought a new philosophy to the shoes. It was beautiful and exaggerated. I wanted to do boots that came up to the bosoms of the girls, but we had to move it down a little because it wasn't very comfortable. If they're given the chance to expand, they're going to be extraordinarily successful. I saw two dresses that John [Galliano] designed for Margiela this weekend and they were divine. Hope is not lost for beautiful clothes."

He's quite right – and such beauty is even more readily available with the speed of the high street and its designer replicates. Does he ever get aggrieved with the many, many high-street homages of his best-known designs?

"I don't care anymore," he says quickly. "Sometimes it's complimentary, but when they're too similar that upsets me. Two years ago, a woman came up to me in Milan and said, 'Do you like my Manolos?' I said, 'well yes I do but these are not Manolos. These are a rip-off.' She took the shoe off and it turned out that they really were authentic. That's how similar copies have become – sometimes I can't tell the difference. Also, they can never replicate the quality."

Part of the myth surrounding Manolo is his appearance. You can't imagine him wearing jeans and a T-shirt, nor being unshaven. He looks exactly how you imagine him to, polished in a well-tailored colourful suit, hair combed neatly to one side and a perfect pair of classic shoes.

"I was born with this mentality since a child," he said. "Maintenance is important even when you're busy. In the morning I have a quick shower, then a shower at night. There's never a big effort – I've never tried to be polished. If you have an old suit that's many years old, you must send it to the cleaners every two weeks or so. That's what you have to do. People have to pay more attention."

"I'm a terrible person to be with and to work with"

Blahnik has a lot of energy, which he ascribes to his mother who he says "was always moving, here, there and everywhere and always in kitten heels". Although he claims his life is "terribly boring" – ("all I do is studio, work, manufacture, work, home, read, bed, boom") – he talks at breakneck speed with an insightful knowledge in everything. The designer also says he's a nightmare to work with – even David Bailey, who shot him as the first ever man to cover Vogue, described him as difficult.

"I'm a terrible person to be with and to work with," he says. "I'm a perfectionist and in this world, that can be a hindrance rather than an advantage. People want everything so quickly. But for my customers, I insist on making sure something that is well done and that will last."

The luxury shoe world is a busy market, but what sets Blahnik apart, what has made him a household name above all others, is the timelessness of his designs and the comfort of his shoes.

"It's paramount," he says. "If they're not comfortable don't buy them or throw them away. I'm pleased to hear it when women say they buy our shoes again and again because they're comfortable. Do you know what I hate? Those very tall platform hooker shoes. They're finished now, but I've seen so many."

Blahnik describes himself as an optimist – and it's an ethos that translates to his often eccentric, decorative designs.

"Even in these hard times, which is not easy anywhere, you have to be positive because you have to be," he says firmly. "Every day is a new day. Even in the face of the most horrific tragedy, you have to think up. What other choice is there?"

Long live the king of shoes.

Manolo: The Boy Who Makes Shoes For Lizards arrives in cinemas on 29 September

...