Ada Hannah Lewis-Hill, philanthropist. Born Liverpool but brought up in a large family in Dublin where she married Samuel Lewis in 1867. They lived in Grosvenor Square until his death in 1901, when she was left a fortune. In 1904 she married William James Montagu Hill. He added her name to his to become Lewis-Hill. See William Burdett-Coutts for more examples of this. Wikipedia describes him as a moneylender to the aristocracy, but he was also an army officer more than 30 years her junior. Possibly the moneylending came after his marriage. Her marriage to William has interesting similarities with that of Angela Burdett-Coutts to her William.
1905 she founded the Ada Lewis Nurses' Institute. 1906 she became one of the two wealthiest women in the UK, the other being Lucy Cohen (one of the Rothschilds), not Angela Burdett-Coutts. Oddly all 3 of these rich women died in 1906.
Having loved music and been a violinist herself, in her will she endowed the Royal Academy of Music and left her Stradivarius violin to the president of the Royal Academy for the use of the Ada Lewis scholars. 1913 the Ada Lewis Women's Lodging House was opened.
One of her younger sisters was the Irish songwriter and composer, Hope Temple (born Alice Maude Davis, 1859 -1938, also known as Mrs André Messager).
Wikipedia gives two dates for her birth: 26 April and 29 June. Nowhere can we find a record of any children born to Ada.
Looking for more on Ada's second husband, we have found a number of records of William James Montagu Hill (who may be our man) in the army, the earliest of him as a 2nd Lieutenant in 1897. 1902-3 he is given as a Lieutenant in the Scots Guard. 1917, as a Captain, he was honoured with a DSO.