I have just completed my research into Horace's story. Sadly he died during the 3rd Ypres offensive (what we all now know as Passchendaele) on 26th September 1917, most probably at the Battle of Polygon Wood. He was 19 years old.
His story can be found here https://wordpress.com/page/oldwhittingtonops.com/342
Please have a look at Horace's and some of the other stories that can be found at oldwhittingtonops.com
If anyone is descended from Horace or any of the other men remembered on the Old Whittington War Memorials and would like to contribute any family stories or photographs please contact me.