Thankfully, it didn't take long to discover that Hoole was preceded by an initial, 'P', i.e. P. Hoole Jackson, and digging around via a Google search and in various sites turns up some interesting hits. Putting together all the jigsaw pieces I was able to gather, I've compiled the following.
Percy Hoole Jackson was born in Prestwich, Lancashire, in September 1892, the son of Henry Jackson and his wife, the former Edith Hoole, daughter of John, a bank cashier, and Elizabeth Hoole. Edith died in 1892, almost certainly in childbirth, aged 24, and it seems likely that her husband, the much older Henry (thirty years her senior) died within a few years. Percy appears to have been raised by his uncle Oswald Hoole (a bank clerk) and his aunt Sarah, with whom he was living when the census for both 1901 and 1911 was taken. Oswald's family included two daughters, a son – all younger than Percy by some years – and his (Oswald's) widowed mother, Elizabeth. By 1911, Percy was working as a clerk for the Co-operative Society.
An account of Jackson's exploits during the Great War appeared in Everyman at War (1930) edited by C. B. Purdom, which can be found here. The book included the following about Jackson's wartime career:
P. Hook Jackson joined the 6th Battalion Manchester Regt. (T.F.) in September 1914. Served in the Dardanelles campaign as a private soldier from May until October 1915. Invalided to Malta with slight wound and dysentery. 2nd Eastern General Hospital, Brighton, from November until January 1916.Wrote songs and verse that was broadcast on the wireless in Manchester as early as 1927 and his stories appeared irregularly in the Manchester Guardian in 1928-43.
__Rejoined Division in Egypt in May 1916. Served in the Sinai campaign as private soldier and scout. Took part in battle of Romani, when the Turkish second attempt on the Suez Canal was defeated with heavy loss to the enemy. Forced marches and desert fighting.
__In February sent to France. Served as scout to the brigade. Wounded and gassed in the Battle of Ypres of September to October 1917. Returned to battalion and served again as sniper and scout. Granted commission as second lieutenant in 1918, and attached to the Lancashire Fusiliers.
In the 1930s he lived at Brook Cottage, Combe-in-Teignhead, nr. Newton Abbot, Devon, and contributed to English Review, Country Life, Christmas Cracker, Woman's Magazine, Great War Adventures, The Price Budget for Boys (1939) and Illustrated.
Still contributing to publications like Country Life and the John Creasey Mystery Magazine in the 1960s.
Jackson died in Penzance, Cornwall, in 1976, aged 84. He was twice married: first to Hettie Jackson in 1917, who died in Newton Abbott in 1944, aged 54; Jackson had separated from his first wife and was already living with Elizabeth Jacka Harry, whom he married in 1944. They had three children: Leon H. Jackson (1938; m. Margaret A. Henson, 1964), Lewis H. Jackson (1941; m. Marjorie Trembach, 1961) and Vivian H. Jackson (1946; m. Nancy Blackwell, 1968). Elizabeth Hoole-Jackson (as she was listed), died in 1977, aged 72.
Maid o' the Moors. London, C. W. Daniel Co., 1924.
The League of the Cat, illus. Douglas Relf. London & Glasgow, Blackie & Son, 1954.
Red Mask. London & Glasgow, Blackie & Son, 1954.
Silent Takes the Trail, illus. Victor Bertoglio. London & Glasgow, Blackie & Son, 1955.
Bird of Gold, illus. Charles Doughty. London & Glasgow, Blackie & Son, 1956.
The Sign of the Glove, illus. Will Nickless. London & Glasgow, Blackie & Son, 1957.
Silent and the Lost City, illus. James Moss. London & Glasgow, Blackie & Son, 1959.
Thanksgiving. Selected poems from the published work of P. Hoole Jackson. London & New York, 1928.
Contemporary Lancashire Poetry, with others, ed. S. Fowler Wright. 1928,