John Sinclair CBE (1860 – 9 December 1938) was a British physician who served as Chief Medical Officer to the General Post Office from 1913 to 1920.
He was educated at Oswestry School and trained as a doctor at the London Hospital.
He was awarded an honorary Doctor of Medicine (MD) degree by the University of Durham in 1900.
He was appointed Commander of the Order of the British Empire (CBE) in January 1920 for his work in the First World War.
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