William Alleyne Cecil, 3rd Marquess of Exeter PC (30 April 1825 – 14 July 1895), styled Lord Burghley between 1825 and 1867, was a British peer and Conservative politician.

[3] Exeter was elected to the House of Commons for South Lincolnshire in 1847, a seat he held until 1857,[1][4] and then represented North Northamptonshire from 1857 to 1867.

[6] In March 1867 Derby appointed him Captain of the Honourable Corps of Gentlemen-at-Arms, a post he held until December 1868,[6] the last nine months under the premiership of Benjamin Disraeli.

They had at least nine children: Lord Exeter died in July 1895, aged 70, and was succeeded in his titles by his eldest son Brownlow, who also became a government minister.

[1] Lady Angela Forbes wrote in her 1919 memoir, Memories and Base Details, of how she "[stood] in wholesome dread, in company, I may say, with her own family" of the formidable Marchioness.