Many thanks for your reply. I would go Caldecote as the most likely as I have seen it used as a birthplace for one of them on a Census.
We are talking between 1834 -ish to 1850 -ish.
I have everything I need from Census, but not birth or baptism details for these people. I do have a couple of marriages -- years only taken from FreeBMD and when I am rich I will order some certificates... but mostly I would like to know if I have all the children for Thomas and Caroline.