Helena Bonham-Carter's famous great grandfather was Henry Herbert Asquith (1852-1928), he served as Liberal Prime Minister of Britain from 1908 until 1916.

Asquith had been born at Croft House in Morley, West Riding of Yorkshire, to Joseph Dixon Asquith (10 February 1825 – 16 June 1860) and his wife Emily Willans (4 May 1828 – 12 December 1888). The Asquiths were a middle-class family and members of the Congregational church. Joseph was a wool merchant and came to own his own woollen mill.

He married Helen Kelsall Melland, daughter of a Manchester doctor, in 1877. They had four sons and one daughter before she died from typhoid fever in 1891. These children were Raymond (1878–1916), Herbert (1881–1947), Arthur (1883–1939), Violet (1887–1969), and Cyril (1890–1954). Of these children, Violet and Cyril became life peers in their own right, Cyril becoming a law lord. Raymond was killed during the First World War.

In 1894, he married Margot Tennant, a daughter of Sir Charles Tennant, 1st Bt. They had two children, Elizabeth Charlotte Lucy, later Princess Antoine Bibesco, (1897–1945) and the film director Anthony (1902–1968).

More Info: en.m.wikipedia.org