On the 1900 Census Stephen Tonkin's household is followed by Benjamin Tonkin, born 26 Nov 1873, England. Wondered if there was a link.
Possibility?
Birth Registration - Benjamin Tonkin, Dec Qtr 1872, Truro**, 5c 155 - mother's maiden name Ellery
Cornwall OPC baptism - St Agnes, Wesleyan Methodist, Benjamin Frederick Tonkin, father John, mother Elizabeth, residence Perranwell, born 9 Nov 1872, bap 26 Feb 1873
** Truro registration district includes St. Agnes
Added - the 1910/1920 Censuses not helping to support this possibility.