With ref. to this edited passage from my original post:
... a detailed memoir of Meyler's life published by his friend Joseph Hunter ... includes a remarkably precise statement that Meyler was a native of Anglesey, and proud of the fact:
William Meyler was born at Newburg, in the Isle of Anglesea, December 13, 1755. His family was respectable; and, with the customary genealogical predilections of the Cambrian character, traced their pedigree to a period early in British History. ... His uncle, the Rev. Thomas Meyler, was at that period the highly respected master of the Free-Grammar school at Marlborough ...
Yet this uncle was clearly a Pembrokeshire man born and bred, as confirmed by the record of his matriculation at Oxford (Alum. Oxon.). So were those ancient Anglesey roots really those of William's mother Jonet?
. . . my research has uncovered some additional information about Jonet's family, and her father's occupation may just provide a useful pointer to their hypothetical Anglesey origins.
As the Spenserians site shows, one of Meyler's poems was a kind of idyll set in the Vale of Clwyd ("Cluyd"); and a will in the NLW's probate database demonstrates that his mother was born Jonet Jones, the daughter of the testator -- Hugh Jones of Pool Park in the parish of Llanfwrog near Ruthin (ob. 1778): see
http://hdl.handle.net/10107/228974 This man was employed by Lord Bagot as land agent for the Bachymbyd estate (a property inherited by the Bagots in the late 17th c. from the Salesbury family of that place). The key link is the naming in the will of Jonet's husband as "Rhoderick Meyler"; but the terms make it clear that Hugh Jones thought very little of the merits of his son-in-law. He left Jonet a £7 10s p.a. life annuity for her own separate use and free from the control of any husband, and added for good measure that if she:
shall at any time or times hereafter live reside or Cohabit with her said Husband Rhoderick Meyler Then in such Case I Do hereby Annul and make Void [the said annuity; and] from the time of such her living Residing [etc ... she] shall be Debarred and Excluded from the payment thereof and of every part thereof.
Despite this obvious antipathy, he went on to leave legacies to his grandchildren Hugh, William, John, Elizabeth and Margaret Meyler -- and, indeed, made Hugh Meyler his sole executor and residuary legatee. (As will be observed, that list makes it plain that the baptisms at Newborough shown in my first post are by no means the whole story.)
As to the Meyler paternal descent, the PCC will of the Revd. Thomas Meyler of Marlborough (above-mentioned uncle of William Meyler of Bath), proved in 1786, firms up Roderick's already likely connection with Pembrokeshire: very fortunately it includes token bequests to the testator's siblings, and mentions a brother Roderick then living. Elizabeth, widowed mother of the siblings, also mentions her sons Thomas and Roderick in her will (dated the very day the American colonists declared their independence!), proved St David's 1777:
http://hdl.handle.net/10107/1010748 -- the full list of her children being William (eldest son), Thomas, Peter, Roderick, Ann, Martha, Grace and Mary, i.e. the very same names, in the same order, as appear in Thomas Meyler's PCC will proved 1786.
The hypothesis of a maternal Anglesey descent for William Meyler might suggest that Hugh Jones could previously have been the agent for some estate in the neighbourhood of Newborough. One or two Google hits (incl. some citing Griffith's PACF) indicate that there was indeed an 18th c. land agent at Baron Hill called Hugh Jones, which briefly raised my hopes. But that man seems to have gone off to live in/near Beaumaris, and his known dates &c seem to make it unlikely that he can have been the person who ended up at Pool Park in Denbighshire. I would obviously be very interested to hear if anyone can spot other plausible candidates.
Evidence from a few dips into the Bachymbyd rentals at the NLW show that in 1762 Hugh Jones had already arrived at Pool Park, but up to (at least) 1754 one John Owens had the agency job. Jonet's marriage was presumably before her eldest known child's baptism in 1755; so the Bachymbyd evidence is not in any way inconsistent with the possibility that the Jones family were living in Anglesey up to the 1750s -- thereby creating the opportunity for a daughter of the house to be wooed by the local exciseman. Without some such theory, it is not at all easy to work out how Pembs. boy met Denbighs. girl, and the memoir's talk about an ancient Anglesey pedigree would probably have to be dismissed as mere fantasy. But I am really indulging in little more than guesswork. Can someone do better?
Rol
