I'd like to return to Rosie's suggestion: to check out all the children of William and Margaret in 1911 census. The siblings seem to be pretty affected by the actions of their father and Mary BELL nee WILKINSON: between 1906 and 1908 the majority of them marry and or move away. One to Winchester; one is already in Erith Kent; two to the Boer War, where one moves on to Australia; three siblings emigrate to Canada-British Columbia; the youngest remains with Mary BELL now TENch; one son continues travelling overseas as an engineer. This son appears to be the closest to his father, working in India with him and the son's family are there too-his infant daughter dies there. Maybe William's legitimate wife was there too and died there. All the siblings are accounted for in 1911 except fo a son Alfred Firth TENCH born 1885, one of the sons who travelled to South Africa about 1908 and a daughter, Margaret born 1876, who may have married a David Davidson, in which case she is accounted for in 1911.