Birth registrations that appear to be a match for a couple of the family:
Births Sep 1927
Fletcher Eva Butler Monmouth 11a 28

From GlosBMD:
Child Surname Child Forename Mother's Former Name Year District Office Register Entry
FLETCHER Eva BUTLER 1927 Forest of Dean Monmouth, West Dean 8

Births Jun 1917
Fletcher Alice Butler Monmouth 11a 34

From Glos BMD:
Child Surname Child Forename Mother's Former Name Year District Office Register Entry
FLETCHER Alice BUTLER 1917 Forest of Dean Monmouth, West Dean 5 116

This suggests that Alice and Eva’s mother was Emily Butler but not yet found a marriage.

Mike