Sarah Murphy, 35, describes her daughter Olivia as “a real toughie”. She was 2½ when she fell ill in June 2005 with an intense fever and mysterious bruising, and had the blood tests that revealed her cancer.

Olivia then had to endure three rounds of powerful chemotherapy that left her weak and in pain, and though the treatment seems to have worked, it has come at a price.

She is in remission, but the toxic drugs she was given have cost her the sight of an eye. The knowledge that her sister, Isabella, is still at risk as the twins approach their fifth birthday next month means that Mrs Murphy and her husband, Justin, a site manager, cannot stop worrying yet.

“Olivia is almost clear but she still has her eye,” Mrs Murphy said yesterday. “They said the cells might die off naturally but obviously it is something hanging over us. It is quite hard but we have always tried to remain positive, although that is easy to say.” Both twins are now at school and coping well. “I don’t think the other children are too aware of the treatment, although Olivia’s eye is quite noticeable now,” Mrs Murphy said.

She worries about Isabella, not least because she is different from her sister in character. “Olivia is the tough one. She is a really strong character. She just gets on with it, whether it is taking drugs or having treatment. Isabella is a real drama queen. You always know when she is ill. If it was to happen to Isabella she would be more awkward. Olivia has really been fantastic through the whole thing.”

“They do fight. Like a lot of siblings they have a love-hate relationship with a lot of jealousies. I think the one thing is that they have been made aware of death before five years old because of other children they have seen in the hospital.”

When the twins’ potential to advance research was pointed out, the Murphys agreed to help immediately. “What we have always said is that anything that would improve the treatment we would be very, very happy to contribute to,” Mrs Murphy said.

“We have seen the families who have gone through all the chemotherapy. Anything which leads to a lessening of the intensity of chemotherapy which can help other families is a good thing. Without research we wouldn’t have had the treatment available to us. If we can give something back we will.”

The family is now trying to lead as normal a life as possible and even go on holidays.“It does cause a strain and you are apart a lot and there are sleepless nights,” Mrs Murphy said. “We went to EuroDisney together last September with other leukaemia families and went to Rhodes last August.”

“We are thankful. We have been lucky. Isabella is always at the back of our minds, but we like to be positive.”

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