[3] Despite the lack of a dowry, George Spencer, Viscount Althorp fell "out of his senses" with Lavinia and offered her marriage.

His parents Lord and Lady Spencer permitted the match, perceiving that Lavinia was pretty, intelligent, and morally acceptable.

[2] The young couple married on 6 March 1782,[1] and had nine children:[4] A rising politician, Althorp succeeded his father as the 2nd Earl Spencer in 1783.

[1] The historian Malcolm Lester describes her as "a strong-minded and strong-willed woman of great erudition and charm [who] was perhaps the pre-eminent hostess in London society".

[1] The biographer Amanda Foreman, however, details less attractive traits, describing her as "moody, vindictive, hypocritical" and "neurotically jealous" of her sisters-in-law the Duchess of Devonshire and the Countess of Bessborough and "a calm liar who maintained a veneer of politeness to her in-laws while freely abusing them in conversation elsewhere.