As the M/C of John/Mary does not appear to be on-line anywhere you may have to get it to confirm their Fathers names/occp's.
In the meantime here are Johns possible Parents on 1861 Census;
1861 Census
Robert Tink, 50, Head, Mar, Gardener, born Maisemore
Caroline Tink, 52, Wife, Mar, born Barton, St Mary
William Tink, 16, Son, Wood Sawyer
Robert Tink, 12, Son, Errand Boy
Fanny Tink, 10, Daug, Scholar
Ann A Tink, 8, Daug, Scholar
And your John Turk may have not been born as Turk.
1851 Census
Robert Turk, 40, Gardener/Jouneyman
Caroline Turk, 40
Charles Williams, 14
JOHN Williams, 12
Hannah Williams, 8
William Williams, 7
Robert Williams, 2
Fanny Turk, 1
Only Fanny age 1 is their Daug, all other Williams Children are down as Daug in Law/Son in Law, which means Roberts Step Children.
Anc has the MARRIAGE;
25 Dec 1848
Marriage Place: Gloucester, St Mark, Gloucestershire, England
Robert TURK, Full Age, Bachelor, Gardener, Father ROBERT Turk, Labourer
Caroline WILLIAMS, Full Age, Spinster, Father JOSEPH Williams, Blackksmith
Bride/Groom, made their mark
Witnesses were James Williams and Albina Barton (James signed)
1841 we have;
Caroline William 30
Joseph William 11
James William 9
Charles William 3
John William 2
William William 3 mths
Fanny Turks GRO Birth Reg confirms her Mothers mn;
TURK, FANNY, ****WILLIAMS
GRO Reference: 1850 J Quarter in GLOUCESTER UNION Volume 11 Page 364
Trish