William was the youngest son of James & Elizabeth Callan and lived with them and his two brothers at Massie Street, Cheadle. He was a member of the Cheadle Literary Institute and, like many others, was a keen lacrosse player.
James Callan and his uncle, George, originated from Muirkirk, Ayrshire and had moved to this area to work as road surveyors during the 19th century. James is believed to have married Elizabeth Anderton in the late 1870s and he died, aged 75, in 1895. The 1901 Census shows Elizabeth, aged 47, "living on own means". As well as William, the Census also lists the family as including Jane (aged 27), Thomas (15), James (13) and John (11).
William enlisted, at Sheffield, in the Lincolnshire Regiment in September 1914 (service number 7/12432) and transferred to the Royal Engineers, probably in 1916 or 1917. It is thought that he requested the transfer but it is possible that he had skills useful to the Engineers
Newspaper reports say that he was twice gassed, although it is not known if this was before or after joining "H" Special Company. This unit was itself a gassing company so it is possible that William joined "to get his own back". However, it is more likely that he was gassed through accident.
On the day he died, his unit was in the Bethune/Loos sector. This day the German offensive, codenamed Georgette, was launched against the British First Army. William was killed in the enemy bombardment.
His brother, Private James Callan lost a limb whilst serving with the 9th Black Watch at Beaumont Hamel, on the Somme, whilst his other brother, Lt John (Jack) Callan, was twice wounded during the War. Jack Callan was an officer with the 6th Battalion, Black Watch and, in January 1916, the Stockport Advertiser reported that he was on sick leave at home in Massie Street, after being wounded in the chest.