Editor's note: Max Foster is CNN's Royal Correspondent. Follow him on Twitter. Richard Quest is presenter of Quest Means Business. Follow him on Twitter and Facebook. Read their take on the queen's hospitalization.
(CNN) -- Max Foster: We were told the queen had been taken in on Friday and that she wasn't able to carry out a public engagement in Wales the following day.
The last time she had to cancel a public appearance was last October when she had a bad back. But this is rare indeed.
The queen takes her role extremely seriously and only cancels when absolutely necessary. As if to underline that she carried on with a private engagement at home in Windsor Castle on Sunday, handing out a long service medal to a member of staff.
She must have been battling with pain because she was taken to hospital, for the first time in a decade, on Sunday afternoon. The monarch has also canceled all her plans for the week including a high profile visit to Rome.
The queen will no doubt be thinking this is all a lot of fuss. She epitomizes so much about Britishness including the "stiff upper lip."
But we are talking about the head of sixteen states here, and an elderly one at that. The queen's family and aides are taking no chances with her health and they are concerned enough to want her under direct hospital supervision.
Richard Quest: The palace will want to make sure everyone understands that this is a precautionary measure. The queen may be 86 years old but she enjoys excellent health.
She also hates making a fuss. Her Majesty will have been concerned about the engagements that need to be canceled or postponed. Even today before she was driven to hospital the queen presented long service medals.
The queen was scheduled to go on a two day visit to Rome this week. That is not now taking place. The Italian president has sent his best wishes to her Majesty.
The hospital where she is now staying is the same hospital where the Duchess of Cambridge was admitted in the early days of her pregnancy. It was the hospital where the hoax phone call was made which ultimately lead to the suicide of one of the nurses.
The royal family traditionally stay at the King Edward VII hospital because of its security arrangements and a well-practiced routine for handling these high-profile patients.