Family
On 28 November 1899, Lord Londonderry married the Hon. Edith Helen Chaplin, eldest daughter of Henry Chaplin, 1st Viscount Chaplin, and Lady Florence Sutherland-Leveson-Gower (herself a daughter of the 3rd Duke of Sutherland) at St Peter's Church, Eaton Square and had issue:
Lady Maureen Helen Vane-Tempest-Stewart (1900–1942), who married in 1920 the Hon. Oliver Stanley and had issue: (i) Michael Charles Stanley (1921–1990), who married (Aileen) Fortune Constance Hugh Smith and had two sons; and (ii) Kathryn Edith Helen Stanley DCVO (1923–2004), Lady-in-Waiting to Queen Elizabeth II from 1955 to 2002 and who married Sir John Dugdale KCVO (1923–1994) and had two daughters and two sons.
Edward Charles Stewart Robert Vane-Tempest-Stewart, 8th Marquess of Londonderry (1902–1955)
Lady Margaret Frances Anne Vane-Tempest-Stewart (1910–1966), who married in 1934 (div. 1939) Frederick Alan Irving Muntz and in 1952 (div.1958) as his 3rd wife, Hugh Falkus (1917–1996).
Lady Helen Maglona Vane-Tempest-Stewart (1911–1986), who married, firstly (of three marriages), in 1935 Edward Jessel, 2nd Baron Jessel, and had issue: (i) Hon. Timothy Edward Jessel (1935–1969) who married twice and had issue; (ii) Hon. Camilla Edith Mairi Elizabeth Jessel (b. 1940) who was married and has issue; and (iii) Hon. Joanna Margaret Jessel (1945-1980) who was married and had issue.
Lady Mairi Elizabeth Vane-Tempest-Stewart (1921–2009), who married in 1940 (div. 1958) Derek William Charles Keppel, Viscount Bury (1911–1968), eldest son of Walter Keppel, 9th Earl of Albemarle and had issue: (i) Lady Elizabeth Mairi Keppel (1941–2014) who married in 1962 (div.) Alastair Michael Hyde Villiers (1939–2005) and has issue, and in 1980 (div. 1988) Merlin Hanbury-Tracy, 7th Baron Sudeley; and (ii) Lady Rose Deirdre Margaret Keppel (b. 1943) who married Peter Lathrop Lauritzen, son of George F. Lauritzen, of River Forest, Illinois, U.S.A., founder of a food manufacturing, processing and export firm, and has issue.
Lord Londonderry had an illegitimate daughter with actress Fannie Ward, named Dorothé Mabel Lewis (1900–1938). She first married, in 1918, a nephew of mining magnate Barney Barnato, Capt. Jack Barnato, who died of pneumonia shortly after their wedding. Her second husband, whom she married in 1922, was Terence Plunket, 6th Baron Plunket, and with him, she had three sons: Patrick Plunket, 7th Baron Plunket, Robin Plunket, 8th Baron Plunket, and the Hon Shaun Plunket. Lord and Lady Plunket were killed in an aircraft crash in California in 1938.