Sometime after her husband's death which occurred on 11 June 1864, she became the mistress of the Prince of Wales, who would later succeed his mother, Queen Victoria to the British throne as King Edward VII. He had married his consort Alexandra of Denmark in 1863. According to author John Van der Kiste, Susan bore the Prince an illegitimate child in 1871. He cites in his book Edward VII's Children that one of Susan's confidantes wrote to Edward advising him that the "crisis was due within two or three months", which is presumably a reference to Susan's pregnancy. She allegedly gave birth to the Prince's child in Ramsgate at the end of 1871. Nothing however, is known of the baby's sex or subsequent fate because when Susan died on 6 September 1875 at the age of 36, she took the secret with her to the grave