She died aged 76 at her London town house in 1866, and was buried on 13 April in a vaulted grave at Broadwater and Worthing Cemetery, in plot C4.1–4.10–13, near the North Chapel.
Her estate was worth £400,000.
£45,000 was left to her nieces and nephews, but there was no legacy for her sister Sarah Tebbitt.
She left £5,000 to Dr Collett who attended her last illness, and generous legacies to servants and acquaintances.
One account says that she left the remainder of the estate, plus £30,000 and Charmandean her country house, to Simm Smith.
His brother inherited the other half of the residue, and was to inherit Charmandean after Simm Smith's death.
Another account says that Simm Smith and his brother Samuel were to inherit £180,000.

From 26 April to May 1867, The Times reported the case of Smith and Others v Tebbitt and Others, in which Sarah Tebbitt and two nieces contested her Will "on the grounds of undue execution, incapacity and undue influence."
At the hearing, the legatees declared Ann sane whereas those left out of the Will, led by Ann's nephew, recounted her religious delusions.
It was during this case that the unmarried situation of Ann Thwaytes's mother came to light, because illegitimacy might put Sarah Tebbitt's position of rightful heir in doubt.
On 6 August 1867 the judge cited monomania as her illness, and found that she was of unsound mind when signing her Will, thus making it invalid.
He said, however, that if she had been found to have been in sound mind, there remained the question of possible undue influence by the Smith brothers, putting the validity of the Will doubly in doubt.
She died aged 76 at her London town house in 1866, and was buried on 13 April in a vaulted grave at Broadwater and Worthing Cemetery, in plot C4.1–4.10–13, near the North Chapel. Her estate was worth £400,000. £45,000 was left to her nieces and nephews, but there was no legacy for her sister Sarah Tebbitt. She left £5,000 to Dr Collett who attended her last illness, and generous legacies to servants and acquaintances. One account says that she left the remainder of the estate, plus £30,000 and Charmandean her country house, to Simm Smith. His brother inherited the other half of the residue, and was to inherit Charmandean after Simm Smith's death. Another account says that Simm Smith and his brother Samuel were to inherit £180,000.
From 26 April to May 1867, The Times reported the case of Smith and Others v Tebbitt and Others, in which Sarah Tebbitt and two nieces contested her Will "on the grounds of undue execution, incapacity and undue influence." At the hearing, the legatees declared Ann sane whereas those left out of the Will, led by Ann's nephew, recounted her religious delusions. It was during this case that the unmarried situation of Ann Thwaytes's mother came to light, because illegitimacy might put Sarah Tebbitt's position of rightful heir in doubt. On 6 August 1867 the judge cited monomania as her illness, and found that she was of unsound mind when signing her Will, thus making it invalid. He said, however, that if she had been found to have been in sound mind, there remained the question of possible undue influence by the Smith brothers, putting the validity of the Will doubly in doubt.
Ann Thwaytes