Sotheron-Estcourt was born on 4 April 1801, the eldest son of Thomas Grimston Estcourt, Member of Parliament (MP) for Devizes and Oxford University, son of Thomas Estcourt, Member of Parliament for Cricklade.

He was elected to parliament again in 1835 as MP for Devizes, switched to North Wiltshire in 1844, and continued in the Commons until 1865.

Sotheron resumed the name Estcourt in 1855, and entered Lord Derby's second government in 1858 as President of the Poor Law Board.

Sotheron-Estcourt married Lucy Sarah, daughter of Admiral Frank Sotheron, in 1830.

In 1839, he assumed by Royal licence the surname of Sotheron in lieu of his patronymic in order to inherit his father-in-law's property.