Ivan's brief and painful life was blighted by a combination of cerebral palsy and severe epilepsy. And in the end, it was just one seizure too many.
And when Gordon Brown rose to pay his condolences in Parliament, he was thinking doubtless not just of Ivan, but also of his own late baby daughter Jennifer, who died from a brain hemorrhage aged just ten days old in 2002. The death of a child is an unbearable sorrow that no parent should ever have to endure, he said.
Politics can sometimes divide us, he added, but there is a common bond that unites us in sympathy and compassion at times of trial. For once he was heard in silence, and for once there was no questioning his sincerity.
Gordon Brown and David Cameron are said to dislike each other intensely. Certainly their backgrounds are wildly different. But that shared grief brought them together. There was no way normal political battle could be joined after such a moment. The parliamentary sitting was suspended, and Questions to the Prime Minister abandoned.
It's a terrible twist of fate that the two men who will battle it out for the top job in next year's expected General Election here have each lost a child. Ivan Cameron needed 24 hour care, could not walk or talk, and had to be fed through a tube in his stomach. He was regularly rushed into hospital. His father spent countless nights sleeping on a hospital mattress beside him.
But those who knew the Cameron family say that Ivan brought joy along with the pain. He also reminded our nation that the fundamental beliefs which we share are far more important than the political trivia which divide us.
By Peter Allen