Mis-filed as MARRATT in the WW1 Service Records (WO 363):

William John Joseph HARRATT joined the Royal Engineers in October 1915, declared age 26y 8m, born Northampton.
Served as Regt Nos. 3204 & 526235 until discharge in 1919.

Home address: Northampton.
Married EMILY WHITE in Northampton in 1913. (Surname not in the Record - GRO shows WHITE as mmn for children & for marriage)
Children: Doris Evelyn 1915 & Leslie (John - GRO) 1916.

Anc****y, MAR, pages 84311-84334