Stella McCartney says fashion is "psychology".

The 42-year-old designer investigates her "holistic sense of self" when working on new pieces and wants her clothing to be relevant in today's society.

She explained to The Observer newspaper's The Fashion magazine: "Fashion is psychology, so there's a whole holistic sense of self that I'm thinking about when I'm designing. And of course, I want clothes to be modern and cool and relevant."

Although she's keen to stay "modern" Stella recognises the importance of designing pieces which are timeless and can be passed on through generations.

She added: "At the same time, they have got to be perfectly constructed in the most beautiful fabric, because I want them to last not just your lifetime but your daughter's lifetime and her daughter's lifetime.

"And that's just scratching the surface, because inside of that I am trying to source those beautiful fabrics in a responsible way. I'm trying to show that it is possible to have a business in luxury fashion that is led by a woman."

The British style icon doesn't want her customers to consider the complex process behind designing, but wants them to enjoy how the items look and feel.

She said: "I don't want anyone to feel any of that. I want the woman who comes into my store to feel at ease, to see a dress and try it on and love how it makes her feel. At that moment, what I want to do is uplift that woman."