There ARE some horrible comments here and some silly ones too.
The hospital is one used by the Royals as the Queen is its patron for a start - his consultant will be there, the staff know him, it's small (58 beds)so security is easier than at a huge NHS hospital where other patients and visitors might be impacted on if there were armed police all over the entrances, any tests and results can be turned round far quicker than in the NHS without inconveniencing NHS patients etc etc etc.
He had major abdo surgery 2 years ago which we don't know what for so it could be connected with that - bowel, prostate, kidney- who knows- and if he is having some symptoms they want to keep an eye on him.
Have some understanding.