Hi Jen,
The service records were fire damaged during WW2 so they can be difficult to read. This is what I have found:
Howard Vincent Harris enlisted on 11th December, 1915 at Walsall.
Service No. 308003
Address 43 Bentley Lane, Walsall
Age 29 Occupation Leather Worker
Born in the parish of Bloxwich
Married.
Height five feet four and a half inches
Next of kin: Wife Eliza Harris address as above.
He was in the Army reserve until he was mobilized and joined the ASC at Bradford on 17th March, 1917.
Occupation Skilled Saddler
Married Eliza Ward at St. Andrews, Walsall on 25th December, 1908
Children:
Mabel Elizabeth Harris born 8th October, 1909
Howard Vincent Harris born ?3 (month too faint) 1910
William C ?? Harris, birthdate too faint to read
George? born 1917
It does not look as though he served abroad.
Would you like us to find him on the 1891 and 1901 census?
Regards,
Mo