A mystery donor has given £100,000 to an ill four-year-old boy to enable him to go to the US for potentially life-saving cancer treatment.
The parents of Zac Oliver from Broseley, Shropshire, who has a rare strain of leukaemia, have been campaigning to raise £500,000.
The donation, first reported in the Daily Mail, ensured the family reached its target.
NHS England has been asked to comment on why Zac cannot be treated in the UK.
Zac's mother Hannah Oliver-Willetts, 33, who is an occupational therapist, said she received a phone call out of the blue telling her "not to worry" and "pack her bags", reassuring her it was not a hoax.
Hours later, the money appeared in their bank account.
"It takes a very special type of person to do that", she said.
Zac was diagnosed with acute lymphoblastic leukaemia in May.
He is believed to be the only child in the UK with the near-haploid strain of the disease, a condition that affects only one in 200 childhood leukaemia patients worldwide.
He is not eligible to receive the type of treatment he needs in the UK because his condition does not currently meet criteria set by the NHS, his parents said.
Doctors at the Children's Hospital of Philadelphia say its 17-week CAR T-cell therapy will give Zac a 60 to 80 per cent chance of survival, she added.
Speaking on the BBC's Victoria Derbyshire show on Wednesday, Mrs Oliver-Willetts said: "Hopefully we will come back with a cured little boy who will get his life back."
His parents managed to raise £400,000 in just a few weeks thanks to the donations of neighbours and friends in Shropshire.
They ran a special event called ZacFest in Telford Town Park last weekend that is understood to have raised about £10,000.
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X-Factor judge Simon Cowell also pledged to donate £50,000 to the appeal.
Zac will now undergo chemotherapy at the Princess Royal Hospital in Telford and will travel to the US after a week of recuperation at home.
"Everyone who saw a donation pot and threw a quid in, every child who emptied their money box... we can't thank everybody enough", Mrs Oliver-Willets added.