Such differences in lifespan are considered in aging circles to be extremely large, but not uncommon.
Harry, sixth in line to the throne, will quarantine in accordance with coronavirus guidelines so that he can attend the ceremonial funeral at Windsor Castle.
Philip, Elizabeth's husband for more than seven decades and the longest-serving consort in British history, died on Friday aged 99.
Reactions from major public figures in Britain and around the world.
Philip’s support for Jewish and pro-Israel causes ran deep, and his mother was recognized by Yad Vashem as “righteous among the nations" for sheltering Jews during the Holocaust.
Elizabeth is the sovereign, but in family matters it was Philip who was viewed as the head of the family.
"The issues raised, particularly that of race, are concerning. Whilst some recollections may vary, they are taken very seriously and will be addressed by the family privately."
A royal source stressed that the admission was not an emergency and said that the queen, 94, remained at Windsor where they have stayed during the pandemic.