Beaufort's extant correspondence of 200+ letters and journals contained portions written in personal cipher. Beaufort altered the Vigenère cipher, by reversing the cipher alphabet, and the resulting variant is called the Beaufort cipher. The deciphered writings have revealed family and personal problems, including some of a sexual nature. It appears that between 1835 and his marriage to Honora Edgeworth in November 1838, he had incestuous relations with his sister Harriet. His diary entries, in cypher, show that he was tortured by guilt over this.