Henry Silcock's parents were James Charles Lionel Silcock, District Inspector of police, and his wife Muriel Dorothy Latchford, daughter of John Latchford, an army doctor. Henry attended Campbell College, Belfast; and studied at Trinity College Dublin 1934-38 - his BA was conferred in 1939, his MA in 1946. He was Captain of the University's golf club.
Henry started teaching at The Leas in 1938/39. He left in 1945 to be an assistant house-master at Oundle, but returned after only one term: in 1946, when The Leas moved back from its wartime home in the Glenridding Hotel, Henry was invited by Francis Fetherstonhaugh to join him as joint headmaster.
In his first two years as headmaster, Henry was much occupied in the conversion of a former RAF gymnasium into the school chapel, in which the first service was held on 12 December 1948.
As headmaster, Henry led services in chapel and (late evening) in First Form. He would often read this verse (by the Victorian religious writer Mary Anne Hearn, pen-name Marianne Farningham):
As headmaster, Henry was also responsible for formal punishment beatings (with slipper, gym-shoe or stick), which he gave with more gusto than accuracy. He taught mathematics to First Form, and inspired some to scholarship success. His attention however was often diverted by almost constant indigestion (a high-fibre diet might have worked wonders). His cheeks were always very red, turning blue at heated moments.
Henry's principal enthusiasms at The Leas were sports and the school grounds, in particular the cricket square and the pitches on it; he coached first-game sports, wrote match-summaries and player-appreciations for the school magazine, and drove teams to and from matches. Outside school, his main enthusiasm is reported to have been horse-racing.
Thanks to his wife's strident calls, Henry was often simply known as Henry; also as Bilko (presumably from the slight assonance with Silcock, as Henry had none of the comic mannerisms of Phil Silvers).