Ledwich, Thomas Hawkesworth (1823–58), surgeon and medical school principal, was born in Pembroke, Wales, one of at least three sons of Edward Ledwich, solicitor, who practised in Waterford, and Catherine Eleanor Ledwich (née Hawkesworth). Edward Ledwich (qv), antiquarian, was his grandfather. After his education at Dr Graham's school, Waterford, and his apprenticeship to Mr Mackessey in the same city, he entered the Original School of Medicine, Peter St., Dublin (1841), becoming licentiate (1844) and fellow (1845) of the RCSI.
He was appointed demonstrator (1844) and lecturer in practical anatomy and physiology (1847–58), and subsequently, with his brother Edward Ledwich and Dr Thomas Peter Mason, FRCSI (1817–1900), became the principal proprietor of the Original School. Impressed by the importance of pathology in the understanding of health and disease, he largely pioneered the combination of theoretical and practical teaching in private medical education and amassed a valuable collection of specimens. An accomplished and popular teacher, he revitalised the school, attracting the largest classes in Dublin, and established its excellent reputation, particularly for the teaching of anatomy, which contributed to the fame of the Dublin school of medicine. A slight, pale, and gentle man, he devoted all his time and energy to study and to the school, which at the students' request (1868) was renamed in his memory the Ledwich School of Medicine.
His most important publication, The practical and descriptive anatomy of the human body (1852), became a standard work; it was written from original observations in conjunction with his brother Edward, who revised it in 1864 and 1877. He published valuable reviews in the Dubl. Q. Jn. Med. Sc. and several articles, some of which were translated and appeared in the Bulletin Thérapeutic de Paris. In July 1858 he was appointed surgeon at the Meath Hospital. Throughout his life he had suffered from ill health; he died suddenly (29 September 1858) at his home in York St., Dublin, and was buried in Mount Jerome cemetery, Dublin. He married (29 July 1856) Isabella Murray; no evidence of children has been found.
His brother, Edward Ledwich (1817–79), surgeon and medical school principal, was born and educated at the diocesan school in Pembroke. He studied at the Original School (1845) and was admitted licentiate (1848) and elected fellow (1852) and council member of the RCSI. Appointed lecturer of anatomy and physiology (1850) at the Original School, he (with Mason) established the principle of private teaching, excelled as a ‘grinder’, and directed the school after the death of his brother Thomas. As surgeon to Mercer's Hospital (1861–79), he was an indifferent clinical teacher, and according to Cameron had an aversion to major operations. He died 19 February 1879 at his home, 7 Harcourt St., and was buried in Mount Jerome cemetery, Dublin. From c.1869 he had contributed £50 annually for improvements in the hospital and bequeathed £1,150, which became the nucleus of the Ledwich building fund and financed a new hospital extension. His nephew Edward L'Estrange Ledwich (1855–1927), physician, great-grandson of Francis L'Estrange (1756–1836), PRCSI, and son of William Ledwich and Elizabeth Ledwich (née L'Estrange), demonstrated and lectured in anatomy (1879) at the Ledwich School until its amalgamation with the RCSI (1889), when he was appointed college anatomist. He served as physician (1897–1913) and consulting physician (1913–27) to Mercer's Hospital and published Surgical and descriptive anatomy of the inguinal and femoral regions, considered in relation to hernia (1884).