Birth registration on GRO says name was Jean Theodore, mother's maiden surname: Vonholst.
|TOURRIER, JEAN THEODORE
|GRO Reference: 1846 S Quarter in MARYLEBONE Volume 01 Page 148|
I would record his forenames as they were registered, then put the Theo/Theobald in preferred name field. (As he wasn't English English, both forenames can go in the "first name" field, as he appears to have followed the continental habit of using whichever forename suited him at the time.)
EDIT -- your "notes" should be below the biography, under == Research Notes == header (above Sources header).