A young girl with cerebral palsy is to have a life- changing operation overseas after the couple who scooped the UK's biggest lottery win offered to pay for the procedure.

Four-year-old Isabel Wallis, from Musselburgh, East Lothian, will have the surgery in the US in November, after EuroMillions winners Chris and Colin Weir provided the funds to make it happen.

The youngster's parents hope the procedure will give their daughter the chance to live without having to use a wheelchair.

Her mother, Kate Horne, said: "I have been at breaking point trying to look after Isabel, but the generosity of everyone around us has always kept me going.

"Receiving the donation from the Weirs was overwhelming, words cannot describe it. It means that Isabel gets the operation she needs almost immediately, and the care she needs afterwards. It also means I can go back to being more of a mum."

Ms Horne and Isabel's father, Rory Wallis, have been raising funds over the past six months to help pay for the operation.

They raised nearly £15,000 from friends, family and supporters through their online page www.facebook.com/isabelsfund.

The existing funds can now be set aside to cover rehabilitation and physiotherapy after the surgery.

Mr Wallis, whose colleagues at Wetherspoons in Musselburgh also raised more than £1000 for the fund, said: "People have been so incredibly supportive and it means so much to us. Now that Chris and Colin have stepped in to top up the fund, we couldn't be happier."

The Weirs, from Largs, Ayrshire, won more than £161 million on the lottery in July last year – the largest jackpot ever in Europe.

Mrs Weir said: "Kate and Rory have worked so hard to raise the money needed for Isabel's operation, so it was a pleasure to help.

"We hope that the operation will give Isabel the chance of an active life. We wish her well."