Interesting details, Malcolm- I just had a (very) quick look at the Whitakers, and
thepeerage.com's details on Leith Ingham Tomkins Whitaker were somewhat unclear: his parents are given as Lt-Col Ernest Leith Tomkins (1869-1927), of Grayshott Hall, Hants. (probate record gives 7, Rue J. P. Feret, Dieppe, France), and Isabelle Marie (1875-1908), dau. of David Francois de Pury, but it also states 'He was given the name of Leigh Ingham Whitaker at birth. He was adopted by an unknown person. In 1916 his name was legally changed to Leith Ingham Tomkins Whitaker', citing BLG 1969 and an e-mail from a Camilla Whitaker (presumably the daughter of Jeremy Whitaker mentioned in the first post). From the above details it seems the death of his mother, along with his father's military career, would have led to his adoption.
Kelly's Handbook to the Titled, Landed and Official Classes 1969 somewhat clarifies matters: 'Whitaker, Maj. Leith Ingham Tomkins, s. of Lt-Col. Ernest Leith Tomkins and nephew and adopted s. of Alexander Ingham Whitaker'.
With this in consideration,
thepeerage.com also gives (citing the abovementioned e-mail from Camilla Whitaker) Isabelle Marie de Pury's sister, Berthe Catherine (1873-1956), as marrying Alexander Ingham Whitaker (1857-1933), of Grayshott Hall (probate record gives 29, Kensington Court, Kensington), [per the BLG 1871 pedigree below, 7th] s. of Joseph Whitaker (1802-1885) and Eliza Sophia, dau. of William Sanderson. Grayshott Hall was owned by the Whitaker family from 1884, when the abovementioned Joseph, a wine merchant, already in possession of Hesley Hall, Tickhill, Yorks. (this presumably being the 'Whitaker of Hesley Hall' family in BLG 1900, per BFI; there's also apparently a book, 'Whitaker Of Hesley Hall, Grayshott Hall, Pylewell Park, And Palermo', by Robert Sanderson Whitaker), formerly of Palermo, Sicily, purchased it from John Rouse Phillips, of a brewing family, details regarding which here:
http://webcache.googleusercontent.com/search?q=cache:TI3hQD6dUDkJ:www.grayshott-archive.org.uk/modules.php%3Fname%3DNews%26file%3Darticle%26sid%3D115+&cd=3&hl=en&ct=clnk&gl=ukThe source for E. L. Tomkins being of Grayshott Hall was Camilla Whitaker; what exactly this entailed is unclear to me given he wasn't a member of the Whitaker family and A. I. Whitaker appears to have lived there.
EDIT: The Whitaker of Hesley Hall pedigree also appears in BLG 1871, showing Joseph (1802-[death date obviously not given, but 1885 as above]) to be fourth son (of six sons and a dau.) of Joseph Whitaker, of West Ardsley [near Leeds], and (m. 1794) Mary, dau. of William Ingham, of Ossett. Joseph senior was s. of Isaac and Sarah Whitaker. The pedigree is headed with the statement 'The family of Whitaker has been established in the West Riding of Yorkshire from a remote period'; the exact meaning of this is- perhaps, as was not uncommon in Burke's publications of that period, intentionally- unclear (and, given the rather oblique wording, not necessarily based on anything other than 'family tradition', pending further investigation- I confess I always wonder in cases like this, given the vast length of some pedigrees, 'if there's such a long and illustrious lineage, why not include it?' The answer often seems to be 'the family don't actually know the details, but it's tradition').