Hi Lisa
No I have found no trace in 1861 however I did find that particular reference but with no other details kind of put it to one side until I got more information. However, as it appears Ann Rankin nee Murphy possibly remarried and moved to Missouri and the last child on baptism records appears to be 1854 - my best guess would be Thomas dying somewhere between 1854/5 and 1861 and Ann Rankin remarrying probably prior to moving to Missouri especially as there appears to be a Charles Williamson 18 Born Louisiana in the family of :
Charles Williamson 30 Born NY. Salesman in paperhouse.
Ann Williamson 42 Born England
Fanny Rankin 16 Born Louisiana
Mary Rankin 15 Born Louisiana
Charles Williamson 18 Born Louisiana
Interestingly Robert Rankin appears from his bio to have started business life in 1870 as a traveling representative of the Johnson and Sawyer Paper Company based in St Louis Missouri. So the picture begins to fit together.
Many thanks for your help
Sarenid