Welcome to RootsChat VicN,
Doesn't help with a cause of death but a death notice:
"VENABLES. - On Sunday, Jan. 31st, 1915, at 24 Ethelbert-crescent, Cliftonville, Knowles Rayson Venables, of "Venray" Crouch- hill N., the dearly loved son of Edward and Annie Venables, aged 21. Friends, kindly accept this intimation."
Tuesday, Feb. 2, 1915 and Wednesday, Feb. 3, 1915
Publication: The Daily Telegraph
"IN MEMORIAM ...
VENABLES - To ever remember our very dearly- loved son and brother, Knowles Rayson Venables, who left us Jan. 31, 1915, aged 21. So sadly missed, tho' always living in our hearts. - Father, mother and his three brothers."
Monday, Jan. 31, 1916
Publication: The Daily Telegraph