Some articles mention William Hosier being an "agriculture graduate"; initial searches in this connection brought up the Hosiers who have farmed at Wexcombe, nr Burbage, Wilts. for nearly a century, but this is either a separate family or a different branch of that treated below. The Hosier family below is clearly strongly linked to farming, however, meaning the identification of William Hosier, if following in family tradition, may well be correct. If the William Hosier who married Stephanie Phillips is the William James Hosier b. 1998 (given his wife's age per articles, not unlikely- there aren't really any other options per what I came across), the genealogy below should be accurate:
William James Hosier b. 1998, mother "Roderick"; Timothy R. B. Hosier m. 1993, Joanna M. Roderick [presumably the Joanna Mary Roderick b. 1967, Croydon, mother "Heaney" (no obvious marriage of parents)] - appears to be third of four sons.
Timothy Roger B[ush?] Hosier b. 1968, of Whitefield Farm, Ogbourne St George, Marlborough, Wilts., farmer, director, Whittonditch Farm Barns Development Ltd building project development; 2nd s. of Joshua James Hosier (1944-), of Manor Farm, Buttermere, Marlborough, farmer, director, J. J. Hosier Ltd, Joshua Hosier & Son Ltd, and Susan, dau. of Herbert William Arthur Plank (1920-1979), of Woodbridge House, Coxhill Lane, Potterne, Devizes.
J. J. Hosier [only? Also 1 dau.] s. of Joshua Henry Bush ("Ben") Hosier (1905-1997), of Rivar Farm, Shalbourne, Marlborough, formerly of Manor Farm, East Grafton, Wilts., farmer, director, Joshua Hosier & Son Ltd, and (m. 1936) Catherine Elizabeth ["Kit"] (1911-2010), dau. of Herbert John Sainsbury, of West Lavington, Wilts., building contractor (bricklaying).
J. H. B. Hosier s. of Joshua Hosier (1872-1960), of [per probate] "Little River, Shalbourne" [this presumably related to RivAr Farm; probate records seem to often have at the very least minor errors], formerly of Manor Farm, East Grafton, Wilts., farmer, director, Joshua Hosier & Son Ltd and (m. 1902) Ethel Marion (1882-), dau. of Bush, of Frome, Somerset. [An Ethel M. Bush b. 1882 in the household of Charles Bush, tailor, at East Pennard, Somersets. per 1891 census]
Joshua Hosier 3rd s. of Joshua Hosier (1832-1902), of Dovey's Farm, Callow Hill, Brinkworth, Marlborough, and Sarah Elizabeth (1834-), dau. of Henry Fricker, of St Margaret's Street, Bradford, Wilts., plumber and painter.
Joshua Hosier b. Somersetshire per census records; probably more could be discovered with research. In the 1851 census he is in the Laverton, Somersets. household of his widowed grandmother, Sarah Hosier (b. 1767), "farmer of 170 acres emp. 7 lab[ourers]".