With thanks to someone called 'In the Know' who kindly pointed out to me that Hilary Douglas Clark Pepler is not a female but a male poet. The name of course in English can be either masculine or feminine - I have a cousin Hilary, a cousin Elliott both female and a neighbour called Cameron who, unlike Cameron Diaz, is male.
Harry Douglas Clark Pepler was born in Eastbourne. During WW1 he worked for London County Council.
Under the pen-name H.D.C.P., Hilary published the following WW1 poetry collections:
"God and the dragon: rhymes" (Douglas Pepler, Ditchling, 1917) and
"Pertinent and impertinent: an assortment of verse" (St. Dominic's P., Ditchling, 1926).
Source: Catherine W. Reilly "English Poetry of the First World War A Bibliogaphy" (St. Martin's Press, New York, 1978)