On the Cumnock War Memorial he is C.S.M. Robert W Brown of Ayrshire Yeomanry but it seems he transferred to the Highland Light Infantry.
He fell on 25 March 1918 and is on the Pozières Memorial at the Somme.
Cumnock Connections tree
Name: Robert W. Brown Birth Place: Old Cumnock, Ayrshire Residence: Kintyre, Argyllshire Death Date: 25 Mar 1918 Death Location: France & Flanders Enlistment Location: Ayr Rank: L/Corporal Regiment: Highland Light Infantry Battalion: 12th (Service) Battn Number: 42630 Type of Casualty: Killed in action Theatre of War: Western European Theatre Comments: Formerly 2460, Ayrshire Yco.