Pauline,
War diaries rarely mention men by name, but if you do want to follow, what are probably the movements of this Ernest Vickers, then here are the references, assuming that he stayed with 47 (2nd London) Division throughout:
WO 95/2738 is the ref. for 1/20th Battalion London Regiment right through from March 1915 to May 1919. This diary is available to download for £3-50 via Documents Online.
WO 95/2739 includes 141 Infantry Brigade; Brigade Machine Gun Corps from January 1916 to February 1918.
WO 95/2722 and WO 95/2723 cover 47 Battalion Machine Gun Company from March to July 1918 and August 1918 to April 1919 respectively.
Phil