A 'green' granny from Oxford, who is converting her home into the country's most eco-friendly house, has won a national competition.

Averil Stedeford, 73, beat thousands of entrants to scoop the DIY Award at the Observer Ethical Awards ceremony. The judges included the Hollywood actor Woody Harrelson, TV gardener Monty Don and Zac Goldsmith, of the Ecologist magazine.

Retired Sobell House doctor Mrs Stedeford was recognised for the dramatic transformation she has made to her house in St Leonard's Road in Headington.

After her husband died two years ago, she set about making her house the most eco-friendly in England.

Sheep's wool fleece insulation has been added to the walls, and super heat-retaining glass containing argon has been fitted to the windows.

An underground water tank is being fitted in the back garden to collect rainwater for use in washing machines, flushing the toilet and outside taps.

Solar panels to heat water are being fitted to the roof, as well as a wind turbine and photo voltaic panels to generate electricity. She also plans to build an extension made entirely from timber.

Mrs Stedeford also drives a Toyota Prius hybrid petrol-electric car, which runs on a battery at low speeds, recharges itself going down hills and cuts out when stationary.

As well as the honour of becoming Britain's DIY queen, Mrs Stedeman also won a £1,000 voucher to spend on eco-friendly building products.

She said: "The threat of climate change is enormous. I've got grandchildren and I don't want them to grow up in a world where there is a risk of flooding and all sorts of other environmental disasters.

"I am also a Christian and I love the world, and I want to look after it."

Mrs Stedeman has employed a team of top architects to help her find the most environmentally friendly materials and methods.

When she has completed the redesign, she plans to put all the information about the steps she has taken on a website so that everybody else can access it for free.

Judges said: "Averil is an example to us all. When you look at how much she has achieved in her own home, anybody should be able to make radical changes, simple things that can lighten our environmental footprints on the earth's resources."