Upon his death on 28 September 1846, she found herself possessed of the whole of the Waldegrave estates, including residences at Strawberry Hill, Chewton in Somerset, and Dudbrook in Essex, but with little knowledge of the world to guide her conduct.
[1] Her third husband, who was a widower and her senior by thirty-six years (being sixty-two at the date of the marriage, while she was only twenty-six), was the eldest son of Edward Harcourt, Archbishop of York, and a follower of Robert Peel, whom he supported in Parliament as member for Oxfordshire.
Of her conduct to Harcourt, Sir William Gregory wrote in his Autobiography: "She was an excellent wife to him, and neither during her life with him nor previously was there ever a whisper of disparagement to her character.
On 20 January 1863 she married Chichester Samuel Parkinson Fortescue (afterwards Lord Carlingford), and from that time until her death her abilities, as well as her fortune, were devoted to the success of his political career and of his Liberal Party.
Her salon at Strawberry Hill or at her residence in London, 7 Carlton Gardens, was from the date of her fourth marriage until her death, sixteen years later, one of the chief meeting-places of the Liberal leaders.
Flashes of wit occasionally came from her lips without effort or preparation, but she forgot her epigrams as soon as she uttered them; indeed she was known on more than one occasion to repeat her own jests, forgetting their origin and attributing them to other people.
Her friends among politicians and men of letters included the Duc d'Aumale, the Duke of Newcastle, Edward Lear, Lords Grey and Clarendon, M. Van de Weyer, Bishop Wilberforce, Abraham Hayward, and Bernal Osborne.
"[2] Lady Waldegrave died without issue at her residence, 7 Carlton Gardens, London, on 5 July 1879, and was buried at Chewton, where Lord Carlingford erected a monument to her memory.