This post is long overdue as I’ve been sat on a treasure trove of information sent by Paul Walker. His father, Frederick George Walker and Fred’s two brothers, Herbert Walker and John William (Billy) Walker all served with 87th Anti-Tank. All survived the war.
This post will be updated but firstly here’s another excellent photo sent by Paul. This is part of the Chagford series but this time it’s a whole battery! 
The Walker Brothers are circled. Freddie Friend and Harry Marsh (holding the dog) are also visible.
87th Anti-Tank Regiment, Royal Artillery (7th Devons) 