David Cameron has said "common sense in the end won out" after five-year-old Ashya King was finally reunited with his parents.
Speaking on Good Morning Britain, the Prime Minister said: "Having had a disabled child often in hospital, often fed through a tube those pictures absolutely meant so much to me.
"The thought of having your much-loved boy separated from you for all those hours and days I can't think of anything more painful for a parent."
Ashya King's parents told the Daily Mail they fled the UK after being told NHS treatments would leave him with life-long disabilities.
The head of the police force which applied for a European Arrest warrant against the parents of Ashya King has now urged their release.
A British mother whose son's life was saved by proton therapy has told ITV that she defied NHS doctors' advice to pursue the treatment.