A British boy is dying of a brain tumour. His distressed parents discover a life-saving treatment, available only in another country. Heartless doctors refuse to refer the child to the foreign clinic. Instead, they insist on going ahead with conventional treatment which, the parents fear, will turn him into a "vegetable". The distraught parents seize their son from the hospital and take him abroad. The UK authorities overreact wildly, issuing an international alert for the family. The parents are found in Spain and arrested, causing an outcry and interventions from leading politicians.

This sequence of events has been widely reported in the past week. It is what a great many people believe about the controversy over five-year-old Ashya King, who is currently in a hospital in Malaga. Many of them have signed internet petitions or written furious blogs, citing the case as an example of the authoritarian state or the arrogance of doctors. The problem is that the story I've outlined simply isn't true, starting with this basic fact: Ashya isn't dying. Despite headlines using the hugely emotive phrase, he isn't "terminally ill".

In fact, his chances of surviving five years are between 70 and 80 per cent, as long as he receives prompt chemotherapy followed by radiotherapy. His tumour, which is called a medulloblastoma, was removed at a major teaching hospital, Southampton General, just over six weeks ago. To maximise his chances of recovery, chemotherapy should have started within four to six weeks of surgery. It didn't, because his parents fell out with doctors in Southampton. The treatment they want is available at a private clinic in Prague, but that isn't where they headed when they left the UK. They actually returned to the south of Spain, where they have a holiday home, and where they were staying when Ashya first showed symptoms earlier in the summer.

Obviously, the diagnosis of a brain tumour in a young child is devastating for any family, and no one doubts that Brett and Naghemeh King want the best for their son. But it is possible, despite being an eventuality discounted by most of the people making inflammatory comments, that even the most loving parents will sometimes make bad decisions in moments of extreme stress.

In this instance, the Kings did their own research on the internet and read about a form of radiotherapy known as proton beam treatment, which isn't available in the UK.

In pictures: Ashya King's case Show all 22 1 /22 In pictures: Ashya King's case In pictures: Ashya King's case Ashya King Brett King, back left, and Naghemeh King, right, accompany their son Ashya King (5) center, as he arrives for pre-cancer treatment examinations at the Motol hospital in Prague, Czech Republic In pictures: Ashya King's case Ashya King Ashya King (5) arrives for pre-cancer treatment examinations at the Motol hospital in Prague, Czech Republic In pictures: Ashya King's case Ashya King Brett King, father of five year old Ashya King, talks to members of the press after holding a press conference at his lawyer's office in Seville, Spain In pictures: Ashya King's case Ashya King Brett and Naghemeh King, parents of Ashya King, attend a press conference in Sevilla, Spain. The British parents are heading to see him at a hospital in southern Spain following release their from custody after United Kingdom authorities dropped accusations of child cruelty against them In pictures: Ashya King's case Ashya King British couple Brett (L) and Naghemeh (2L) King leave Soto del Real Prision in Soto del Real, near Madrid, Spain In pictures: Ashya King's case Ashya King Brett King leaving Soto del Real prison near Madrid, Spain after British authorities dropped the case against him and his wife for taking their son Ashya from Southampton General Hospital without the consent of doctors In pictures: Ashya King's case Ashya King Naghemeh King leaves Soto del Real Prision in Soto del Real, near Madrid, Spain In pictures: Ashya King's case Ashya King Ashya King in hospital with his mother In pictures: Ashya King's case Ashya King Journalist work outside the Materno Infantil Hospital where Ashya King is hospitalized in Malaga, Spain In pictures: Ashya King's case Ashya King Ethan Dallas and Sanjay Ganatra, friends of the family, deliver a petition of over 100,000 names calling for his parents' release from a Spanish jail PA In pictures: Ashya King's case Ashya King Spanish judge Ismael Moreno arrives to the National Courts to take statement to the parents of Britain's five-year-old boy Ashya King, in Madrid, Spain In pictures: Ashya King's case Ashya King Ashya King parents's lawyer, Juan Isidro Fernandez Diaz, arrives at the National court in Madrid AP Photo/Andres Kudacki In pictures: Ashya King's case Ashya King Spanish policemen stand guard as a police van carrying the parents of Ashya King arrives at the courthouse in Madrid JAVIER SORIANO/AFP/Getty Images In pictures: Ashya King's case Ashya King Ashya King’s parents after their court appearance BBC In pictures: Ashya King's case Ashya King Ashya King's father explained why he took his son to Spain in a video uploaded to YouTube In pictures: Ashya King's case Ashya King This photo of Ashya King being examined by doctors in hospital was posted on Facebook by his brother, Naveed Facebook/Naveed King In pictures: Ashya King's case Ashya King Ashya King and his brother Naveed Facebook/Naveed King In pictures: Ashya King's case Ashya King Ashya King on a hospital bed Facebook/Naveed King In pictures: Ashya King's case Ashya King A CCTV still issued by Hampshire Police of Ashya King with his father Brett King at around 4pm yesterday PA/Hampshire Police In pictures: Ashya King's case Ashya King The exterior of Southampton General Hospital where Ashya King, who has a brain tumour was taken by his parents from the hospital without the blessing of doctors In pictures: Ashya King's case Ashya King Hampshire Constabulary said there are 'serious concerns' for the life of Ashya King as he needs constant medical care. Officers said his parents - Brett, 51, and Naghemeh, 45, - boarded a cross-Channel ferry from Portsmouth to Cherbourg at 4pm yesterday with Ashya's six siblings PA/Hampshire Police In pictures: Ashya King's case Ashya King Ashya King, who has a brain tumour and was taken by his parents from hospital without the blessing of doctors

There is no general ban on referring NHS patients to have this treatment, although it is very expensive; around 400 patients, most of them children, have been sent abroad to undergo it since 2008. In suitable cases, the NHS will pay for the family's travel and accommodation as well as the treatment. But proton beam radiotherapy is recommended in only a tiny proportion of cancers – around 1 per cent, according to Cancer Research UK.

Ashya's doctors insist they took a clinical (not financial) decision that it would not be better for him than conventional radiotherapy. Because his parents disagreed, the doctors referred his case to a body called the NHS Specialised Services Proton Clinical Reference Panel. The panel confirmed the hospital's opinion that Ashya was not a suitable candidate, but even then his doctors in Southampton went on talking to the parents to try to establish what they would be happy with. The Kings suggested they would be able to fund the treatment themselves, by selling their holiday home, and discussions continued until just before they took him to Spain nine days ago.

Since they appeared in Spain, members of the family have made emotional videos and press statements denouncing the behaviour of doctors in the UK. Ironically, when Ashya first became ill, the Kings brought him back to England to be treated by the NHS. Now they've changed their minds, but it is worth remembering that they are desperate for good news. Last week, NHS Choices issued a clear warning about the marketing of "emerging" treatments, stating unequivocally that "some overseas clinics providing proton beam therapy heavily market their services to parents who are understandably desperate to get treatment for their children". The statement added that it is "not clear whether all children treated privately abroad are treated appropriately".

Video: Explanation of proton beam treatment

When the Kings first removed Ashya from hospital, it was widely reported that the family were Jehovah's Witnesses. Southampton General Hospital denies releasing this information to the media, and it does not seem to have had any bearing on Ashya's treatment to date. But the fact that his parents belong to a millennial religious cult – members believe that the end of the world is imminent and only 144,000 human beings will be saved – suggests that they might not be entirely open to rational argument. Maybe that is why they have not taken up an extraordinary offer from the Health Secretary, Jeremy Hunt, to fly an oncologist to Spain to reassure them about the treatment Ashya would receive in the UK.