Recorded in several forms as shown below, this unusual and interesting name is of medieval English origin. It was a nickname for a small or delicately built person, referring to the bird, the 'Titmouse'. The bird's name derives from the pre 7th century Norse word 'tit' and a prefix indicating 'of small size', with the Olde English pre 7th century word 'mase', which was the original name of the bird. The surname development has included in the surviving church registers of the city of London Jane Tittmouse (1651), John Tittimus (1656), Catherine Titmarsh (1664) and Mary Titamas (1690). The modern surname includes Titmus, Titmas, Titmuss, and Tittmus. An example of recordings is that of Anne Titmus, the daughter of Robert Titmus, christened on the 15th January 1659, at the church of St. Michael, Wood Street. The first recorded spelling in the church registers may be that of Kathren Tetmos, who married Lambart Harmanes, at St. Giles Cripplegate, London, on September 23rd 1564. This was during the reign of Queen Elizabeth Ist, known as "Good Queen Bess", 1558 - 1603. Surnames became necessary when governments introduced personal taxation. In England this was sometimes known as the Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.