Hello tudorbriars, nice to meet you.
A tip: if you start by telling us what you know about your man (that we don't know unless you tell us), it could help a lot.
About when and where was he born, whom did he marry, where did he live, who were his kids, do you know whether he had siblings; what records do you have about him? You are probably wanting to find out who his parents were -- ?
Someday, someone who knows something about him might happen on your post (or you could have rare luck and it could happen sooner!) but more likely, someone who doesn't know about him might be able to help find some info. And everyone will be happy to try!
A Thomas Shackell birth was registered in Tiverton reg dist in 1839, and that Thomas is with parents Richard and Ann in Sampford Peverell in 1841. However, he seems to have become a grocer in St Pancras, London, with wife Amelia, by 1871. He seems to have been the only Thomas in Devon from that time onward, so yours must have been earlier.