On 11 Jul 1848 [his father] George Augustus Cranley Onslow (age 35) and [his mother] Mary Harriet Anne Loftus were married at St Nicholas' Church, Kenilworth.

On 07 Mar 1853 William Onslow 4th Earl Onslow was born to George Augustus Cranley Onslow (age 39) and Mary Harriet Anne Loftus at Old Alresford, Hampshire.

In 1855 [his father] George Augustus Cranley Onslow (age 41) died.

In Oct 1870 Arthur George Onslow 3rd Earl Onslow (age 92) died. His great nephew William Onslow 4th Earl Onslow (age 17) succeeded 4th Earl Onslow, 4th Viscount Cranley, 7th Baron Onslow, 8th Baronet Onslow of West Clandon in Surrey, 9th Baronet Foote of London. [his future wife] Florence Coulston Gardner Countess Onslow (age 17) by marriage Countess Onslow.

In 1875 William Onslow 4th Earl Onslow (age 21) and Florence Coulston Gardner Countess Onslow (age 21) were married.

On 23 Aug 1876 [his son] Richard William Alan Onslow 5th Earl Onslow was born to William Onslow 4th Earl Onslow (age 23) and [his wife] Florence Coulston Gardner Countess Onslow (age 23).

On 22 Jul 1881 [his daughter] Gwendolen Florence Mary Onslow Countess Iveagh was born to William Onslow 4th Earl Onslow (age 28) and [his wife] Florence Coulston Gardner Countess Onslow (age 28).

In 1885 [his daughter] Dorothy Evelyn Augusta Onslow Countess Halifax was born to William Onslow 4th Earl Onslow (age 31) and [his wife] Florence Coulston Gardner Countess Onslow (age 31).

The London Gazette 25615. St. James's Palace, August 5, 1886. To be Lords in Waiting in Ordinary to Her Majesty:—

William Hillier (age 33), Earl of Onslow, in the room of William, Lord Kensington, resigned.

William Hale John Charles (age 46), Earl of Limerick, in the room of Henry James, Lord Hothfield, resigned.

John-Major (age 43), Lord Henniker, in the room of Thomas, Lord Ribblesdale, resigned.

John Adrian Louis, Earl of Hopetoun, in the room of Frederick Henry Paul, Lord Methuen, resigned.

William Buller Fullerton, Lord Elphinstone, in the room of Thomas John, Lord Thurlow, resigned.

On 13 Nov 1890 [his son] Victor Alexander Herbert Huia Onslow was born to William Onslow 4th Earl Onslow (age 37) and [his wife] Florence Coulston Gardner Countess Onslow (age 37).

In 1903. John Collier (age 52). Portrait of William Onslow 4th Earl Onslow (age 49).

On 22 Feb 1906 [his son] Richard William Alan Onslow 5th Earl Onslow (age 29) and [his daughter-in-law] Violet Marcia Bampfylde Countess Onslow (age 21) were married. He the son of William Onslow 4th Earl Onslow (age 52) and [his wife] Florence Coulston Gardner Countess Onslow (age 53).

Before 15 Oct 1906 [his son-in-law] Rupert Edward Cecil Lee Guinness 2nd Earl Iveagh (age 32) and [his daughter] Gwendolen Florence Mary Onslow Countess Iveagh (age 25) were married. She by marriage Countess Iveagh. She the daughter of William Onslow 4th Earl Onslow (age 53) and [his wife] Florence Coulston Gardner Countess Onslow (age 53). He the son of Edward Guiness 1st Earl Iveagh (age 58) and Adelaide "Dodo" Guinness Countess Iveagh (age 62).

On 21 Sep 1909 [his son-in-law] Edward Frederick Lindley Wood 1st Earl Halifax (age 28) and [his daughter] Dorothy Evelyn Augusta Onslow Countess Halifax (age 24) were married. She the daughter of William Onslow 4th Earl Onslow (age 56) and [his wife] Florence Coulston Gardner Countess Onslow (age 56).

On 23 Oct 1911 William Onslow 4th Earl Onslow (age 58) died at Hendon Barnet. His son [his son] Richard William Alan Onslow 5th Earl Onslow (age 35) succeeded 5th Earl Onslow, 5th Viscount Cranley, 8th Baron Onslow, 9th Baronet Onslow of West Clandon in Surrey, 10th Baronet Foote of London. [his daughter-in-law] Violet Marcia Bampfylde Countess Onslow (age 26) by marriage Countess Onslow.

On 03 Aug 1934 [his former wife] Florence Coulston Gardner Countess Onslow (age 81) died.