It appears that there were two children (I would guess a boy and a girl) and if your Vincent was one of them then he was born before 1845.
The Hobart Courier 1 February 1845
Mary Ann McIntosh charged Vincent Spencer Pennington with not maintaining his illegitimate children, two in number. After some abuse on both sides, they agreed each to take one child. Miss McIntosh, however, insisted on taking the boots off the poor child.