"Oh what a tangled web we weave ..." - an apt description of this man's marital arrangements, as found in the WW1 Service Records (as MARSH):

In October 1902, declaring age 24y 9m, born Preston, Brighton, Sussex, occupation French Polisher, GEORGE MARSH joined the Dragoons - Regt No. 5043. He declared himself as unmarried, next of kin being younger brother FREDERICK (5042 Dragoons).

On 16 October 1892 CECIL MARSH married spinster LAURA BEATRICE BOX at Brighton.

Three children were born (ALL registered with mother's maiden name WYATT):
- HAROLD ARTHUR surname SUTHERLAND 14 July 1905;
- ELSIE FLORENCE (MARSH) 31 August 1907;
- DORIS MAY (MARSH) 21 June 1913.

The 1913 baby's allowance was claimed for in October 1914. His "wife" signed as L B FLUDER, address: 39 Southampton Street, Brighton.

Laura (nee BOX) left him long before this ("he treated me cruelly") and in April 1915 wrote (from 52 Clevedon Road, Balsall Heath, Birmingham) to the Army, asking for separation allowance. She had heard that he was sending the allowance to "another woman". She also wrote that she had a 16-yr old daughter in Canada (could this be FLORENCE ELSIE MARSH, registered Q1 1893 Brighton?)

The Army started to investigate. The Officer In Charge realised that the 2 marriage certificates submitted were IDENTICAL.
And then, annoyingly, the papers end....

It looks as though he was CECIL FLUDER, born Q4 1873 Brighton.
Married a possibly pregnant Laura Beatrice BOX as CECIL MARSH in October 1892.

Was left by Laura and lived with another woman (SUTHERLAND? nee WYATT), who signed with the same initials (L B).

George/Cecil served his full 12 years until October 1915, when he was discharged as "Time Expired". The last letter suggests that he rejoined - perhaps under his real name, FLUDER?
Perhaps he preferred to go back into the war, rather than face the battle of 2 women?

Apologies for the length. Perhaps someone can make sense of it. Papers can be found:

Anc****y, WW1 Service Records, MAR, pages 180317 to 180344