Stella Mccartney thinks it's time to ''scream and shout'' about sustainability.

The 48-year-old designer is well-known for her environmentally-conscious clothes, and Stella believes there is now an ''urgency for change''.

She told British Vogue magazine: ''Challenging and questioning things has been drilled into me since I was a kid.

''Over the years I have sat back, quietly working on my sustainability projects in the background. But now, more than ever, there is an urgency for change. If we have to scream and shout to achieve it, then we need to do that to drive action.''

Stella thinks the issue of sustainability is ''a conversation that shouldn't be saved for one day or week a year''.

She continued: ''The world is crying out for change.

''The younger generation is telling us that our house is on fire and that we need to respond like we are in a crisis - because we are, in fact, in a crisis.''

Meanwhile, Stella previously revealed what her life is like as a mother and the head of major fashion brand, admitting she has to get up ''super early'' to fit everything in.

The designer - who has Miller, 15, Bailey, 13, Beckett, 12, and Reiley, nine - shared: ''I start at 6:30am, and by the time I get to work [by bicycle], I feel like I'm literally done for the day. I'm a big hot sweaty mess, too.

''It's just so difficult being in fashion, isn't it? We have to pretend to be so perfect. I'm the one that comes in with a punk-rock kind of 'f**k this perfection.' It's not maintainable, it's not wise, and it's very old-fashioned. So there you go.

''When you've got a job and you've got kids it's when you get to see them, and you have to wake up super early and engage in that moment. Then I try and squeeze in some exercise, and then I go to work. And I try and get back for the book-ending of being a mum.''