Harry Underhill Diplock [also known as Harry U. Diplock and as H. U. Diplock] was born in Brighton, Sussex, England in 1894. His training as an architect may have come from his father Joseph Diplock (c.1863-1901) who's occupation was given as Architect's Assistant in the 1891 England and Wales Census.
H. U. Diplock submitted a design for a bungalow in the Daily Mail Architects Competition for Labour-Saving Bungalows in 1922; and submitted three entries to the Three Bedroomed Cottages Competition organised by the Building Centre Cottage in 1933, one of which was awarded a Special Prize.
His address was given as 185B Latchmere Road, Lavender Hill, Battersea, London in 1911; 19, Ballingdon Road, Wroughton Road, London in 1922; 27, Buckingham Gate, London in 1933; and 49, Sheen Park, Richmond, Surrey in 1957. He died in Reading, Berkshire on 19 September 1957