Yesterday, in a ceremony kept strictly private among King Juan Carlos, his father and mother and his two sisters, Queen Sofia and a handful of close relatives, the family finally fulfilled their wish to bury Don Alfonsito on Spanish soil. Exhumed from a family grave at Cascais, near Estoril, earlier in the week, the infante (prince) - whose full title was Alfonso de Borbon y Borbon - was laid to rest in the family's private pantheon in the monastery of El Escorial near Madrid. He was the last member of the royal family to be returned for burial in the land of his forefathers.
Which of the two royal brothers, if either, pulled the trigger may never be known but Juan Carlos himself was said at the time to have admitted to friends and family that he 'felt responsible'. As a military cadet, he would have been aware of the danger of loaded guns, as indeed would have Alfonso, already a keen hunter and marksman who had bagged a stag and proudly displayed its horns in the family home. Both, it seemed certain, would have been drilled not to clean guns that were loaded.
The two boys had been exceptionally close throughout their exiled childhood, while Franco ruled Spain, and no one doubted that young Alfonso's death had been a tragic accident.
Juan Carlos, friends said, was traumatised by the death of his only brother and never really got over it. The gun that killed Alfonso was said to have been a gift from the dictator, always a closet royalist, to the royal family, despite their long-standing public differences.
The shooting of 29 March 1956 received little publicity under Franco's regime. But thousands of royalists took the risk of crossing to Portugal, many carrying bags of Spanish soil to throw on Alfonso's grave. Even after Franco's death and the resurgence of the monarchy, the shooting was played down in the media, and usually described as un accidente fortuito - a chance accident. Persistent reports from staff of the royal household at the time, however, referred to a pistol and shotgun, with the latter going off.
Though now resting in the land of his forefathers, Alfonso knew little of Spain. He was born, like his brother, in Rome, and brought up first in Switzerland and then in Portugal as his father - Don Juan de Borbon y Borbon, who left a Pamplona hospital to attend yesterday's ceremony - sought to be as close to the homeland as possible during the Franco years.
The key to why it took so long to rebury Alfonso was believed to lie in King Juan Carlos's sensitivities over the tragic day.