Born on 2 October 1901, Crooks graduated in Edinburgh. He moved to London working first as house physician and casualty officer at Great Ormond Street and then, in 1929, as resident medical superintendent. He had taken his FRCS the previous year, and came under the influence of Denis Browne when paediatric surgery was an exciting new specialty. At first he intended to follow a general surgical career, but in 1931 the opportunity of a consultant post at Great Ormond Street led him into ENT surgery, which became his lifelong study. He had a great rapport with children which, combined with his deft technique enabled him to carry out many examinations and therapeutic manoeuvres under local anaesthesia. He was a pioneer in the treatment of the infected antrum, and was a skilled but selective tonsillectomist in an era when wholesale tonsillectomy was the fashion. He built up a large and successful practice, which included several members of the Royal Family. He was appointed CVO in 1958. When the Hospital for Sick Children was being rebuilt in the 1930s he was much involved in planning the main block with the architect, not only concerned with the main concepts but also with details of cleanliness, control of infection, nursing supervision and facilities for parents. Much of what he initiated has become standard practice. Though the war held up development for many years he continued, as Chairman of the Building Committee from 1948 to his retirement in 1967, to guide the formation of the present hospital. He married first in 1931 Irene Heath, painter and writer, by whom he had two daughters. In 1970 he married Caroline Woollcombe. He was himself a lover of the arts and an amateur painter of distinction. In his retirement he extended hospitality to his old friends from Great Ormond Street and exercised his surgical craftsmanship in his workshop on the care of an ancient Rolls-Royce. He died on 16 April, 1980.