Looking into Julian Steele and Pitroddie produced, alongside several company websites, an archived copy of The Times from 1986 with notice of the marriage of Julian Steele- s. of late Brig. W. L. Steele, of Evelick, and Mrs Steele, of Nether Durdie, Pitroddie, Perths.- and Ann, dau. of A. M. Shepherd, of Orbliston, Fochabers, Moray [Alexander Marshall Shepherd, a farmer and veterinary surgeon].
A little digging gave the details of Brigadier William Lindsay Steele, of the Coldstream Guards, O.B.E., who was born 1905 (per records, at Chelsea) and died in 1975. Although a Scottish marriage seemed not unlikely, it seemed equally possible that his was the marriage in 1949 of William L. Steele and Mary A. Garrard, who had previously married (in 1940), Basil E. M. Ball. There appears to be a Mary Steele resident (or previously resident) at Pitroddie based on internet records, so this may well be correct identification of the mother of Julian Steele. (As an aside- given the names now at hand, I suppose "Thomas A. L. Steele" to be "Thomas Alexander Lindsay Steele", but could locate nothing corroborative, perhaps unsurprisingly.)
Julian McCarty Steele, on looking into him next, is given in several sources as father of Barbara, married to a grandson of the 7th Duke of Richmond. Somehow- and regrettably, given it would have greatly simplified my research- I veered off on a tangent following the "Evelick" element, J. McC. Steele being, per some sources, "of Evelick" (n.b.- as was Brig. W. L. Steele, per the Times), which property came to the Steeles from the Lindsay baronets on the death of the 5th and last baronet, whose sisters were his co-heiresses. The eldest, Charlotte Amelia, married Thomas Steele (1753-1823), King's Remembrancer 1797-1823, Joint Paymaster of the Forces 1791-1804, Joint Secretary to the Treasury 1783-91 [son of another Thomas Steele (d. 1775), of Westhampnett, nr Chichester, who represents the apparent limit of possibility tracing back]. Multiple biographical sources give him one son and two daughters, so embarking with that as a premise- plus the fact that the name "William Lindsay Steele", Occam's razor considered, indicates descent from this Steele/ Lindsay marriage, it had to be from amongst the descendants of Thomas Steele's only son, also Thomas (1781-1847), of Guilsborough Park, Northants., a Major-General of the Coldstream Guards, that W. L. Steele derived. However, HIS heir was Thomas Montagu Steele (1820-1890), who per some sources was "elder" and others "eldest" son, which threw something of a spanner in the works. Although I established a younger brother, Augustus Frederick (1823-1884), who had two sons, they were unmarried and living together in 1911, when in their forties, and no evidence indicated any subsequent marriages or issue. I had previously established the issue of Thomas Montagu Steele, and having ascertained the eldest, Thomas Augustus (1858-1892), to have died unmarried and without issue, and tracked down the third and fourth sons and their limited issue, I overlooked somehow until the last moment the aforementioned Julian McCarty Steele, the second son! In researching him more attentively, I found a 1903 marriage to Sybil May, daughter of William John Mure, of North Berwick, W.S., Governor of the Bank of Scotland. There was, however, no issue apparent in the usual records aside from the 1913 birth of Barbara. Fortunately, Google books provided "The Ladies' Who's-Who" of 1930, which had an entry on the widowed Sybil May Steele indicating her issue: Thomas, born 1904, William, born 1905, and Barbara, born 1913 (as aforementioned). Based on this, William Lindsay Steele's middle name and residence at Evelick, the simplest conclusion is that the William born 1905, son of Julian McCarty Steele and Sybil May, née Mure, is the same as the William Lindsay Steele, father of Julian Steele of Pitroddie and grandfather of the Thomas A. L. Steele mentioned in the first post.