It all began as a student project - but now GreenKnickers looks set to stay.

The undies which are kind to the planet, have proved so popular that the zero carbon pants have sold out and a new wedding range is to be launched.

Sarah Lucy Smith came up with the idea for her final project while doing the Eco Design course at Goldsmiths university.

She then teamed up with her school friend Rose Cleary-Southwood, and GreenKnickers was born.

Sarah said: "We started GreenKnickers to prove that ethical can be funny, beautiful and sexy.

"The fabrics are so gorgeous, and super-duper green.They're selling extremely well.

"Some customers say they're the comfiest knickers they've ever worn."

The knickers are made from environmentally friendly fabrics, like organic cotton, hemp and silk. Goods from abroad are shipped by sea and staff travel by bike.

Each pair arrives in a box made from recycled paper and printed with organic vegetable based inks.

The global warming knickers are printed with thermo-chromic inks, and change colour as they warm up.

There is also a range of cycling smalls with removable padding to encourage people to reduce their carbon footprint.

At the moment GreenKnickers operates online, but Sarah said: "If the business continues to be successful I would love to open up a boutique."

Around 80% of the wholesale value goes to the suppliers.

But at a cost of up to £25-a-pair, plus £3 postage and packaging, you will have to pay the price to do your bit.