I checked BFI re: the Wormald family, showing the Heathfield family of that name to last appear in BLG 1972, and that formerly of Sawley Hall in BLG 1952. I checked the 1952 BLG, and didn't find any of the below individuals in either the Wormald of Heathfield or Wormald formerly of Sawley Hall pedigrees; I don't have the 1972 BLG (although at any rate it's perhaps unlikely it would include a branch of the Heathfield family completely omitted from the 1952 edition). The following is what I came across regarding the Wormald family to which (Amey) Benita belonged:
(Amey) Benita Wormald dau. of Leslie Graham Wormald (1890-1965), educ. Eton, Magdalen Coll., Oxon., member of the gold-medal-winning eights rowing team, 1912 Olympics, Maj., R.F.A., M.C., and (m. 1914) Amey Margaret, dau. of Horsey.
L. G. Wormald s. of Sir John Wormald (1859-1933), of Springs, North Stoke, Oxon., and of 87, Sloane Street, S.W.1, educ. Royal High Sch., Edinburgh (some sources give him as born in Edinburgh), M.Inst.C.E., director, Mather & Platt, Ltd, member, Munitions Finance Board, chairman, Industries and General Services Committee of the War Cabinet Committee, lord of the manor of North Stoke, J.P., High Sheriff of Oxfordshire 1916-17, K.B.E. 1919, and (m. 1889) Eleanor Mabel, dau. of Henry Simms, of Oriel Lodge, Bath.
None of the sources I found pertaining to Sir John Wormald, although quite extensive in other detail (as shown above), mentioned his parents. However, based on the birthdate of 1 July 1859 provided in Dod's and elsewhere, the birth record of that date of John Wormald at Edinburgh to Joseph Dawson Wormald and Mary Millar Anderson would appear to be that of the individual in question. There are numerous references to a Joseph Dawson Wormald of Edinburgh, a writer to the signet. Two other sons (one named for his father) were of sufficient note to appear in the Australian Dictionary of Biography:
http://adb.anu.edu.au/biography/wormald-joseph-dawson-9190
J. D. Wormald (senior) was born 1830 at Guiseley, Yorks., to John Wormald and Mary, and married Mary Millar Anderson in Edinburgh 1859. He appears as a lodger in Covent Garden in the 1871 census, 'married', b. 1830 at Yeadon, Yorks. (Yeadon being, apparently, in the Guiseley ward of Leeds). His father, John Wormald, was probably he resident at Wormald Fold, Yeadon in the 1861 census, b. Guiseley, 1797, widowed, and a retired grocer, alongside a grandson, Amos Rawnsley. In the 1841 census, John and Mary Wormald are resident at Bunker's Hill, Otley, Guiseley; by the 1851 census he is widowed, and living alongside (with a Slater nephew and niece) a grandson Albert Rawnsley (corroborating his identity as the same individual as aforementioned, along with the location and his occupation of 'grocer'). Given his son's middle name, 'Dawson', the 1819 marriage of John Wormald and Mary Dawson at Guiseley would very likely be the correct one.
Although both Wormald families in BLG have Yorkshire origins, I can't directly connect this family to either.