Leonie Jerome Leslie.
"Seymour Leslie records, in The Jerome Connexion: '... He ... retired from the Grenadiers after the Egyptian campaign to study at the Academie Julien in Paris ... and ... [in October 1884, as] an idle man-about-town ... married Leonie Jerome, younger sister of Jennie (Lady Randolph Churchill), in New York with the active disapproval of both ... [families], though the American press pointed out that he was heir to Irish estates with twenty thousand gold sovereigns a year virtually tax free. Her mother, Mrs Leonard Jerome, was the perfect snob, even ashamed that Jennie had been born to her in a Brooklyn house, ... and feeling that these Irish squireens were poor fish after the magnificent Churchills. ... The young couple were married in Grace Church [New York], Frank Griswold, the American sportsman, being best man, ... [and] the Leslies [soon] accepted Leonie. ... "
She would go on to have a very close relationship with Arthur, Duke of Connaught (physical or not, I'm not sure) and with his wife, Louise. She was also friendly with his children and maintained a correspondence with their daughter Margaret after she moved to Sweden. (Leonie was not only close to her parents but Margaret was close to Leonie's niece Claire Frewen).
"Anita Leslie records, in Edwardians in Love (London, 197?): '[Leonie Leslie,] when she entered London society as the chic, graceful, but not particularly pretty younger sister of a famous beauty [Lady Randolph Churchill] ..., had to overcome her own sensitivity to comparison. ... Incapable of jealousy, Leonie determined to develop her own assets to perfection. She played the piano as well as her sister, excelling at Chopin, whereas Jennie liked to pound out more tempestuous feelings in Beethoven sonatas, and she had the quickest wit of her generation. But apart from her music and her joie de vivre, Leonie possessed an extraordinary talent for touching the emotional chords in human beings. She wanted people to like her - not an unusual trait - but she also understood the shy and the hopeful: she was genuinely interested in others, and as she grew older her sympathy and wisdom increased. ... "
"It was in the mid-nineties, when they had been married for about ten years, that ... [John Leslie], who had served in the Guards Brigade under the Duke of Connaught, introduced the vivacious Leonie to his former commanding officer. H.R.H. immediately fell under her spell, and remained so until 1942, when he died aged ninety-two. The Duke was a keen professional soldier, and the year 1895 contained a bitter disappointment, for he had hoped to succeed the old Duke of Cambridge as Commander-in-Chief. ... [Leonie Leslie thus entered his] life at a moment when he felt the star of fortune turned harshly. Being a susceptible male, Arthur knew his heart shaken; and being a shy German princess, the Duchess reached out for the gaiety which the American radiated. ... For decades [therefore, Leonie Leslie] "ruled the Duchess and ran the Duke". ...
For two or three years [1900-1904] the Duke commanded the troops in Ireland ... . The Leslies naturally paid frequent visits to the Connaughts' residence in Dublin, and in summer-time the Duke rented Castle Blayney, a large country house seventeen miles from Castle Leslie, so the va et vien could be continuous. ... Leonie and her husband accompanied the Connaughts to India when the Duke went to represent King Edward at the Durbar. ... When in 1909 [sic - 1907] the Duke assumed command of the Mediterranean area it meant that the Jack Leslies went out to enjoy Malta, and [the Leslie] scrapbooks grew heavy with photographs of polo, ponies and parasols. ... In 1913 the Duke became Governor-General of Canada. ... Soon after this, war broke out and Leonie's son, Norman, was killed [N/1-2], as were the sons of almost all her friends. ... In 1915, to help assuage their grief, Jack and Leonie paid a visit to Ottawa. ... In 1917, when the Connaughts had returned to England and the Duchess grew seriously ill, Leonie called daily at Clarence House and was asked to break the final news. ... Throughout the next twenty-five years Leonie would continue to cheer and amuse her Prince. ... [And] from 1898 to 1936 she nearly always spent Whitsun at the Duke's house at Bagshot. ...' "
"[Leonie Lady Leslie died in 1943 receiving an obituary notice in The Times] ... half a column long, in itself unusual for someone not in public life, especially in 1943 when newsprint space was severely rationed. ... Lennox Robinson, the playwright, for many years manager of Dublin's Abbey Theatre, wrote of Leonie ...: "[She was an] ... invisible mender and you would meet at a weekend in her lovely Monaghan home the Governor-General of the Free State and the Commander of the Forces in Northern Ireland. ... She talked brilliantly herself but with the great gift of making everyone else talk a little bit better than they thought they could. ..." [Sir John] ... was a man bereft indeed and only survived her by a few months. ...' "