Context : Bertrand Stewart (December 1872 -- 18 September 1914) worked as a solicitor in London and was also a military officer in the Queen's Own West Kent Yeomanry, he fought in the Second Boer War and World War I. In between the two wars he volunteered to spy on German naval actions. 
Answer : Queen's Own West Kent Yeomanry
In what military organization did Bertrand Stewart serve?