1939 reg has them at 3 Denaby Grove Yardley wood
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I think from the post your grandmother was born a Jervis and it was her Mother (your Gt Grandmother) who was a Faunt.
I was looking for the war diary but at the moment it seems to stop in 1917. 1/5th btn became part of the 48th (South Midland) division - this clip outlines their movement in 1918 and where they were in November.
Frank and his wife Florence plus the 2 girls were there when the register was taken in Sept 1939. The register continued to be updated as girls got married hence their married names showing. When did your Mom marry?
Herbert was b1869 Lichfield (registered as Jarvis). Father was James an agricultural labourer in 1881.
Annie's father Frederick was a cabinet maker and they must have travelled a bit because 2 of Annie's siblings were born in Brazil. Frederick was born in Lincolnshire the son of a wheelwright.