During the First World War it continued to specialise in treatment of wounded officers by a select group of honorary staff, drawn up by Sister Agnes and made up of eminent London surgeons of the time.

[6] The hospital, known simply as Sister Agnes's hospital, initially housed only 12 beds, a basic operating theatre and a staff of six carefully selected nurses, and admitted its first mostly gunshot wounded British Army officers in February 1900, a week after receiving a letter of gratitude from British Army officer General Evelyn Wood VC.

[15] A few days before the onset of the First World War, Sister Agnes drew up a list of 21 honorary staff who would predominantly be the medical men of choice treating wounded officers at 9 Grosvenor Gardens without a fee.

John Percy Lockhart-Mummery became a significant name on the list, probably carried out more operations at the hospital than any other surgeon there, and treated mainly gunshot wounds affecting the colon, rectum and anus.

[16] Others on the list included Sir William Hale-White, Farquhar Buzzard, Joseph Blomfield, George Lenthal Cheatle, and James Sherren, who almost lived at the hospital removing large numbers of bullets and shrapnel from wounded soldiers.

[16] John Thomson-Walker became urologist to the hospital and concentrated on injuries to the genitourinary tract, and for complex operations on the bones Sister Agnes would call upon Sir William Arbuthnot Lane.

[17][18] The future British Prime Minister, Harold Macmillan, was also wounded in the same battle and was treated at the hospital, where he underwent a series of long operations followed by recuperation there from 1916 to 1918.

[19] General Sir Joseph Howard Nigel Poett later recounted in his autobiography (1991) that Sister Agnes had arranged for his treatment to be transferred from Cambridge Hospital to King Edward VII's and that she "was a pretty powerful lady".

[21] During the war, Margaret Greville opened up Polesden Lacey for the purpose of being a convalescent home linked to King Edward VII's Hospital for Officers.

[29] On 10 October 1963, at the hospital, Alec Badenoch, assisted by his juniors David Innes Williams and Joseph Smith, performed prostate surgery on Harold Macmillan.

[5] In 2018, the CQC noted the hospital to have three operating theatres, a level three critical care unit, and radiology, outpatient and diagnostic facilities.

[42] In December 2012, the hospital received international media attention when Catherine, Duchess of Cambridge was admitted, suffering from hyperemesis gravidarum.

[44][45] On 7 February 1999 the businessman and Booker Prize founder Sir Michael Caine fell into a coma after staff were unable to clear a blocked breathing tube.

A leading intensive care specialist concluded that the possibility of death would have been "minimal" had staff at the hospital received proper training.

Sir Michael's widow, Baroness Emma Nicholson, claims that nurses refused to call consultants and doctors despite her husband's distress.

[47] The Baroness also claimed that a subsequent operation on her husband took place at an NHS hospital because the King Edward VII "could not cope.

[49] In light of her husband's death, Baroness Nicholson said:I find it repugnant that NHS beds should be used as a final resource by the private hospitals who set themselves up as being able to cope and yet demonstrably cannot.