Mis-filed & indexed as MARSH in the WW1 Service Records (WO 363):

George William MASH, born Southwark 1885.
Married Susannah Elizabeth BROOKER at Streatham, 2 August 1905
Daughter Marjorie born 27 Sept 1912

Enlisted with the ASC on 5 August 1914. Regt No: 2808
Awarded Military Medal 1918
De-mobbed 1919

Anc****y, MAR, pages 181297-181313