It's quite probably this Thomas Knibbs who was a witness at the marriage on 10 October 1809 between John Mason of Whitchurch, Buckinghamshire, England and Dinah Stevens from Deddington.
__________

The 1851 census for Warwickshire shows Thomas, age 63 living at Yardley, Worcestershire with his two younger daughters Harriet and Fanny.
Name: DOB From: Living at:
KNIBBS, Thomas Head <1788> Dedington-Oxford Yardley
KNIBBS, Harriett Daur <1829> Yardley-Worcester Yardley
KNIBBS, Fanny Daur <1831> Yardley-Worcester Yardley
__________

The following information was provided by Alf Fantham, and has as yet not been confirmed by me personally. Alf obtained the information from the 1841 and 1851 census for Yardley, Worcestershire, and the Yardley Workhouse records.

The Yardley Workhouse records are as follows:

23/4/1830 admitted; 30/4/1830 discharged

Thomas aged 44
Harriett aged 33
William aged 10
Thomas aged 9
Richard aged 6
Robert aged 3
Maria aged 5
Harriett aged 2

(NOTE: the above has also been confirmed by Hilda Elliott, Thomas' great-great-granddaughter. She told me that her grandfather William Knibbs moved from Oxfordshire to Birmingham in 1830 at about 10 years of age with his dad, stepmother and siblings. They lived in the workhouse for a few days).

2/9/1831 admitted
Robert aged 5
Maria aged 7
Harriett aged 3.5

18/4/1834 discharged
Maria

25/7/1834 admitted
Maria aged 10

23/8/1834 discharged
Maria

16/5/1835 discharged
Harriett

We know that Thomas' wife Harriet died in 1831 leaving him with 5 children aged between 6 months and 8 years, so we can only imagine how hard life became for him. It can't have helped that he was living quite along way from his family in Oxfordshire so with no family help available, it's understandable that the workhouse was at times the only solution available to help him survive.

1841 Census living at Grove Lane, Yardley, Gardener
1851 Census living at Poor Lane, Yardley, Gardener
__________

Thomas can be seen at the 1861 census apparently living alone:
Thomas KNIBBS 1789 Deddington Oxfordshire Head Yardley Worcestershire
__________

Thomas died aged 77 years.

Noted that Maria's burial was on the same day as the Christening of her younger son Thomas, so it is assumed that she may have died at childbirth.

Maria's baptism date is provided by Alf Fantham