Sir Henry Sessions Souttar CBE FRCS (14 December 1875 – 12 November 1964) was a British surgeon with a wide breadth of interests. He trained first as a mathematician and engineer. His engineer’s training enabled him to design and make new types of surgical instrument. His mathematical training made him a leader in setting out the first British guidelines for Radiotherapy. In 1925 he pioneered "blind" open heart surgery on a patient with congenital heart defect. This was not repeated until 1948.[1]