Hi Sandy
I've now got Joseph's marriage certificate from 1856 at St Leonard's Glapthorn (to Elizabeth Marriott), which confirms his father as Thomas Palmer, Publican. In the 1841 census, I've found a 15 year old Joseph Palmer serving as an apprentice in neighbouring Oundle - in fact on New Street, Oundle, which I think is the road which leads out of Oundle towards Glapthorn. It all seems to fit with the research done in the mid-1990s except that I can't find the 1826 baptism yet.
Thanks for your help
Regards
Richard.