I note all the baptisms you mention on Ancestry but no census returns, I did see the baptism for Edwin & Alfred on freereg, it notes Father John a Labourer abode Underriver. Mary Ann & John were baptised together on 16 Aug 1859 but Mary Ann was born 16 Feb 1858. Wiiliams baptism also on freereg.
GRO registrations below. Mothers Maiden name YOUNG on all
CROUCH, ALFRED
GRO Reference: 1855 S Quarter in SEVENOAKS UNION Volume 02A Page 318
CROUCH, EDWIN
GRO Reference: 1856 D Quarter in SEVENOAKS UNION Volume 02A Page 340
This one not on GRO but on freebmd but a different quarter?
Births Mar 1859
CROUCH Mary Ann
Sevenoaks 2a 309
CROUCH, JOHN
GRO Reference: 1859 J Quarter in SEVENOAKS UNION Volume 02A Page 370
No registration for William on GRO or freebmd?
Colin