I could not find William on the England Census after 1851, is the death below for him or did he emigrate to another county? However this seems unlikely when the 1851 Census records that he has a farm of 620 acres employing 20 labourers. It is more likely that he died. More research needed.
England & Wales Census 1851 "England and Wales Census, 1851," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:SGZX-57T : 20 October 2017), William Stagg, Bishopstone, Wiltshire, England; citing Bishopstone, Wiltshire, England, p. 18, from "1851 England, Scotland and Wales census," database and images, findmypast (http://www.findmypast.com : n.d.); citing PRO HO 107, The National Archives of the UK, Kew, Surrey.
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