Louisa's portrait was painted by
John Vanderbank; in the picture, she wears "a fancy dress of pink and black".[4]
A myth has grown up that the family home of
Longleat House is haunted by Louisa's ghost, grieving over the death of her lover, who was discovered and killed by her husband. There is no historical evidence for the existence of the lover.[5] Her friend,
Mrs Delany, wrote in her memoirs:"I know some who had higher virtues than she had, but none with fewer faults. Her husband's ... loss is irreparable."[6]
The viscountess died in childbirth[6] at her home in Grosvenor Square, London, and was buried in the traditional Thynne family resting-place of
Longbridge Deverill, Wiltshire.[7][8] The 3rd viscount succeeded to the Carteret estates on the death of Louisa's brother, Robert Carteret, 3rd Earl Granville, in 1776.
^G.E. Cokayne; with Vicary Gibbs, H.A. Doubleday, Geoffrey H. White, Duncan Warrand and Lord Howard de Walden, editors, The Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Extant, Extinct or Dormant, new ed., 13 volumes in 14 (1910-1959; reprint in 6 volumes, Gloucester, U.K.: Alan Sutton Publishing, 2000), volume XII/2, page 589.