I'm afraid there just doesn't seem to be enough to work with, so I have to throw in the towel, despite some promising leads!
Facebook friends included a William and a Louise Holborow, from which I managed to locate other individuals including some turning out to be siblings (as follows) and based on a memorial post and BMD records establish them to be children of Richard W. Holborow, of Tetbury, and his first wife, Devina Mona Mary (1920- pre-2017), née Rule. Along with William, who is gay (which does not of course preclude the possibility of a previous marriage and issue, although U.K. records do not indicate such), is another son, James Richard (b. 1953), who m. 1977, a Theresa A. Isaac and had issue a son (b. 1988) and two daus (b. 1979 and 1984). He appears to have married secondly, 2004, Virginia V. Clarke (the above is corroborate by electoral roll and other sources). Given Alice Holborow's birth to mother 'Greatorex' but no apparent marriage, the possibility exists of there not having been one; the relationship would fit timewise with James Holborow's marriages, but this is of course only supposition.
Richard W. Holborow (regarding whom I was unable to locate very much information; no very likely birth or death records) was married secondly in 1981 to Anthea Kathleen (1944-), dau. of Reginald Alfred Henry Reardon[-]Smith (possibly a scion of that baronetical family?) of Green Farm Cottage, Farmborough, nr Bath, and Rona Kathleen, dau. of Capt. Wilfred Haden Hickman, 1st/ 6th South Staffordshire Regiment, descended from Sir Alfred Hickman, 1st Bt. The above corroborated by marriage records and Debrett's.
Given the ages of his children (the eldest, Victoria, b. 1944, the youngest, William, b. 1958), it would be reasonable to place Richard W. Holborow's year of birth between, say, 1900 and 1925; this would appear to bar a close relationship to the Holborows related by marriage to the Earls of Courtown, as I mentioned in a previous post:
George Holborow, of The Red House, Alderholt, Dorset was, on further research, Rev. George Holborow (1898-1966), of 222, Botley Road, Oxford [per probate record], formerly of The Red House, Alderholt, of Kettering, Northants., and of Wangford, Suffolk. He was educ. Exeter Coll., Oxon. (B.A. 1922) and Ripon Hall, in Oxford, was rector of Kettering and Hon. Canon of Peterborough Cathedral, formerly formerly of Ringsfield with Redisham Parva, Suffolk, and curate of Beccles 1923-6. His wife (m. 1924) was Barbara Stella (1892-1971) [of Pilgrims Cottage, Fressingfield, Diss, Norfolk per probate; at the time of their son Geoffrey's marriage they must have been separated, because 'Mrs Barbara Holborow' was given at that time as of Fressingfield. They had three sons, which is where Richard W. Holborow as above is firmly excluded; eldest son, David George (b. 1925), educ. Repton, Exeter Coll., Oxon. (M.A. 1948), Emmanuel Coll., Cantab. (Dip.Ed. 1949), was director, N.Z. Institute of International Affairs, formerly N.Z. Ambassador to Brazil (res. Chile; 1978-81), the Philippines (1981-4) and South Korea (1980-4) m. Rowena Joan, dau. of Tom Husband [possibly had issue; haven't researched this]. Second son, Christopher Adrian (b. 1927) was an eminent ENT surgeon according to his father's obituary, provided by his mother, in the Emmanuel College magazine (
https://www.emma.cam.ac.uk/publications/EmmaMagazine2016.pdf ); he may have married and had issue but haven't checked as isn't really relevant here; third son Geoffrey (1929-2015), as above, founder, Stratton & Holborow land agents, vice-president, Council of Land Agents, O.B.E. (1979), High Sheriff of Cornwall 1977, m. Lady Mary, dau. of 8th Earl of Courtown.
I can't locate a U.K. birth record for George Holborow, nor any likely individuals in the 1901 or 1911 census, suggesting him to have been born elsewhere; the possibility exists that Richard W. Holborow, seemingly grandfather of Alice E. Holborow, was his brother or possibly even nephew, but lacking evidence no relationship can be established. There are Holborows at Tetbury in 1901 and 1911 census records, but nothing I can really use to confirm anything, unfortunately.