This should get you started:

Birth Registration from GRO Index:
Name: Mother's Maiden Surname:
WHINTOUR, JOHN CHARLES LEWIS
GRO Reference: 1872 S Quarter in MONMOUTH Volume 11A Page 30

This tells us that mother's maiden name is LEWIS.

Possible marriage of parents:
Marriages Jun 1870
Lewis Caroline Monmouth 11a 36
WINTOUR Richard Monmouth 11a 36

A transcript of this marriage can be found in the Parish Registers on this site.

Mike