She was born on 14 July 1906, the daughter of Brian Charles Durant Kemp-Welch[4] of Kineton, Warwickshire, England, and was educated by a governess, and at a finishing school at Les Tourelles, Brussels, Belgium. The Kemp-Welch family were 'solid county Warwickshire stock',[5] appearing in Burke's Landed Gentry.[1] Her brother was the cricketer George Kemp-Welch who married the eldest daughter of Stanley Baldwin.
She married Captain Peter Trayton Kenward[6] of the 14th/20th King's Hussars, employed in his family's brewing business,[7] at St Margaret's, Westminster, in 1932,[1] and adopted his name. They divorced in 1942, leaving her with a nine-year-old son.[1] To pay his fees at Winchester School, she worked as a dame (house matron) at Eton College.[1] Captain Kenward remarried, to Patricia (1918–1957), daughter of Bolton Meredith Eyres-Monsell, 1st Viscount Monsell, in 1947,[8][9] and in 1958 to Bridget Catherine Elizabeth Tucker (1928–2015).[10][11]
Her Tatler column was originally called "On and Off Duty in Town and Country", becoming "Jennifer's Diary" in 1945.[1] She took it to Queen (from 1970 Harpers & Queen) in 1959.[1] She retired in 1991, when she was aged 84.[1] Her obituary in The Daily Telegraph described her as "insufferably snobbish and crotchety", recounting her ferocious treatment of her assistants (many of whom resigned in tears), her propensity for long-running feuds (including, particularly, with Margaret, Duchess of Argyll), and her persistent snubbing of Tatler's social editor, Peter Townend.[1]
She appeared as a castaway on the BBC Radio programme Desert Island Discs on 14 December 1974.[12]
She was made a Member of the Order of the British Empire (MBE) in 1986.[1] Her autobiography, Jennifer's Memoirs: Eighty-Five Years of Fun and Functions, was published in 1992.[13]
She died on 24 January 2001 in London.[14]