Had a look to see if I could connect these Dewhursts to another family of that name I'd been working on recently; no such link, but the following nevertheless:
Charles Frederick Dewhurst of New Meadow House, Winchcombe, Cheltenham, Glos., entomologist (head of entomology, Papua New Guinea Oil Palm Research Association Inc. 2005-2013, ret.), F.R.E.S., F.L.S.; his wife's details Richard already provided.
He s. of Col Frederick Wynford Dewhurst (1897-1979), of Pound Cottage, also of Crapstone House, Buckland Monachorum, Devon, late Royal Marines, by his wife (m. 1945) Patricia Bene Pennefather (1908-), dau. of Sir Thomas Richard Pennefather Warren, 8th Bt.
Col F. W. Dewhurst s. of Wynford Dewhurst (1864-1941), of 145, Belvedere Road, Burton upon Trent, Staffs., sometime of France, Impressionist painter, R.B.A., council member, Buckinghamshire County Council 1907-10, born Thomas Edward Smith; adopted later name by deed poll whilst an art student in France (according to. He m. Antonia Frederika Otillia Hedwig Caroline (1876-1951), dau. of - von Bulow, of that aristocratic family of Mecklenburg. This site (albeit user-produced, so not infallible) quotes several sources regarding Wynford Dewhurst, furnishing us with such details as that the Smiths were a 'relatively affluent family'.
Thomas Edward Smith (Wynford Dewhurst) s. of James Robert Allen Smith (1833-1897), of Hawthorn Grove, Stockport, formerly of Newton Heath, Manchester, a merchant and 'owner of land and houses', formerly cashier and commercial clerk, by his wife Ellen, dau. of John Dewhurst. Other children seem to have used the Dewhurst name as surname; Frederick Howard Smith Dewhurst married at Moss Side, Manchester in 1915, his father's name being given as James Robert Allen Smith, as above.