sooky, from the info provided earlier by JJ, you have Reginald's death at the age of 25 in 1918 druing WW1. The additional info on one of the links by JJ being:
Son of Joshua Bright Harrison and Edith Alice Harrison, of 45, Steele Rd., Leytonstone, London.
Given Reginald's age, he looks to have likely been living at home at the start of war maybe. The address for parents in 1918 may help you with further details.
The fact that it names his parents as next of kin indicates he was single at the time of his death.
Potential memorial for him here
http://twgpp.org/information.php?id=3168438 at the City Of London Cemetery And Crematorium, Manor Park.
Monica