Was Robert Ambrister Charles Cameron's Nephew?

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A relatively minor footnote in the history of 19th century Anglo-American relations involves the campaign led by Andrew Jackson into Florida in 1818. In the course of what is sometimes called the First Seminole War, two British subjects, Alexander Arbuthnot and Robert Christie Ambrister, were captured, subjected to a court martial at Jackson's direction, and executed in April 1818.

While Ambrister's ancestry is rarely mentioned, it has been stated that he had gone to the Bahamas seeking the assistance of his uncle, the Governor of New Providence (Bahamas), in furthering his military career. The governor at this time was Charles Cameron, a younger son of the banker Donald Cameron of Essex and his wife Mary Guy. If in fact the mother of Robert Ambrister was a full sister of Charles Cameron, the following would then be an accurate account of his descent from James IV, King of Scots.

1. James IV, King of Scots = Agnes Stewart [not married]
2. [illeg.] Lady Janet Stewart = Malcolm, 3rd Lord Fleming
3. Margaret Fleming = John Stewart, 4th Earl of Atholl
4. Jean Stewart = Sir Duncan Campbell of Glenorchy (d. 1631)
5. Sir Robert Campbell of Glenorchy = Isabel MacKintosh
6. Margaret Campbell = John Cameron (dvp bef 1647)
7. Sir Ewen Cameron of Lochiel = NN MacLean
8. John Cameron of Lochiel (d. 1747/8) = Isabel Campbell
9. Archibald Cameron (exe. 1753) = Jean Cameron
10. Donald Cameron, younger son = Mary Guy
**11. NN Cameron = James Ambrister, Esq.
12. Robert Christie Ambrister

*I have seen no other reference to a sister, or half-sister, of Charles Cameron. Also, I have seen to date no information concerning Robert Ambrister's sibling(s).

Scholar Commons website (USF) addressed an Ambrister store in the Tampa area:

In several of the various books written about Florida since 1817, there are mentions of a store that was established by Robert Ambrister at Tampa Bay.

**Note from Cameron Collections blog author:  Have not found this marriage; at this point I have no proof that Ambrister was related to Charles Cameron