Find Ancestors

I’m hoping your collective family history know how and abilities to ferret out information might help me with documentary evidence to support pointers from my DNA matches. I have a small group of shared matches. We all link to each other in DNA terms. The closest match is descended from a brother of my great grandfather. 2 matches have small trees, a 3rd has a larger tree that is wholly US based and I can’t yet see the connection to England. By checking and building back the 2 small trees I have found a common link between them, documentary evidence indicates that they are both descended from James Clarke and Ann Slator. James in turn being the son of John Clark(e) and Jane Bailey, who married in 1803 in Terrington St Clement Norfolk. The couple appear to have migrated around the ”Fens” with children born in Norfolk, Cambridgeshire and Lincolnshire. They eventually settled in Tydd Gote, Lincolnshire (part of the parish of Tydd St Mary). I’m not convinced I have found all of their children as I have some gaps, but that is just an aside.

My 2x Great Grandmother was Harriett Clark(e) born mid to late 1850’s (her age is inconsistent on various documents and I haven’t managed to find her on census data as a child, or find a birth registration – I posted on this issue a while back and no one turned either of these). On her marriage in 1874 she named her father as John Clark (deceased). John and Jane had a son John born Parson Drove, Cambs abt. 1821. At least those are the details when he appears on the 1851 census with his widowed mother and shown below at Tydd Gote -

Jane Clarke Head Widow Female 70 1781 Cottager Terrington St Clement, Norfolk,
Mary Clarke Daughter Unmarried Female 44 1807 Nurse Walpole St Andrew, Norfolk
John Clarke Son Unmarried Male 30 1821 Ag labourer Parson Drove, Cambridgeshire
William Bennett Grandson Unmarried Male 18 1833 Ag labourer Tydd St Mary, Lincs

This census is the only place I have been able to find a John Clark(e) that fits in terms of the above. I haven’t been able to find a baptism, or a death registration prior to 1874, that fits. Of course it doesn’t help that John Clark is quite a common name, or that the “Fens” are not wholly in one county.

Can anyone find further entries for John that might help establish whether he is Harriett's father or not?