Prince Philip will remain in hospital for the next few days after being admitted earlier this week on the advice of his doctor.
The duke is in hospital for "observation and rest" after becoming unwell.
It's understood Philip is in "good spirits".
"Following consultation with his doctor he is likely to remain in hospital for observation and rest over the weekend and into next week. As we have said previously, the doctor is acting with an abundance of caution. The duke remains in good spirits" a royal source told the Daily Mail.
The Daily Mail understands Philip is aware of the Harry and Meghan situation unfolding outside his private room.
It was recently confirmed by Buckingham Palace that Prince Harry and Meghan will not return to their royal duties.
This is a decision that makes formal, and final, the couple's split from the royal family.
It's believed Philip was told by the Queen about their decision to not return as working members of the royal family and the statement she was going to release on the situation.
Prince Philip and his grandson Harry have shared a close bond but a recent book suggested Philip was left shocked by Harry and Meghan's decision to walk away.
Ingrid Seward, author of Prince Philip Revealed, said Philip "walked away" from the situation after feeling that his advice was being ignored.
"For Philip, whose entire existence has been based on a devotion to doing his duty, it appeared that his grandson had abdicated his for the sake of his marriage to an American divorcee in much the same way as Edward VIII gave up his crown to marry Wallis Simpson in 1936," Seward's book said.
Due to Philip's condition, it's thought Harry is currently self-isolating at California home so he can return to England if his grandfather's condition worsens.
Harry would also be exempt from having to quarantine if the United Kingdom adds the United States to its "red list" of countries.
Royal family members do not have to isolate in a hotel upon arriving from red list countries due to special dispensation, similar to diplomatic immunity.
Philip, who turns 100 on June 10, is in hospital for an undisclosed reason although it is not coronavirus-related and not an emergency admission.
"His Royal Highness the Duke of Edinburgh was admitted to King Edward VII's Hospital in London on Tuesday evening," Buckingham Palace said.
"The duke's admission is a precautionary measure, on the advice of his royal highness's doctor, after feeling unwell. The duke is expected to remain in hospital for a few days of observation and rest."