Hi Binka,
I'm not sure where Knilesworth is but a possible explanation as to why John uses different names could be that he was born illegitimately to a Miss Winspear who later married a Garbutt (with Mr Garbutt possibly even being John's actual father)
Extracted IGI christening:
JOHN WINSPER
Birth 23 JUN 1802 - Christening 29 AUG 1802 Hawnby, Yorkshire
Mother ELIZABETH WINSPER
Extracted IGI marriage:
ELIZABETH WINSPEAR - JOHN GARBUT
Marriage 13 NOV 1804 Hawnby, Yorkshire

Added:
I suppose you've seen this
member-submitted record on the IGI?
JOHN GARBUTT WINSPEAR - HANNAH STONEHOUSE
Marriage 22 AUG 1835 Lastingham, Yorkshire