Is that you C A? Super to hear from you!!!! Hope you've been well!
Lovely to get a notification out of the blue about more action on this long-dormant thread!
It's funny: I haven't done much at all in the family history space for several years, let alone looking into the Burgoyne family. Coincidentally yesterday I had a moment to turn my attention to Hardy family - Dorothy Maddick Burgoyne's family - with some success.
Speaking of Dorothy Maddick Hardy - her husband William Burgoyne (born Kingsbridge, Devon in 1783) was one of two known sons of another William Burgoyne (born Blackawton, Devon 1747).
For Field Marshal Sir John Fox Burgoyne to be a great uncle of Maria Theresa Burgoyne, I think he would need to be a sibling of Maria's grandfather.
William Burgoyne (born 1783), who married Dorothy Maddick Hardy, was Maria's grandfather.
William Burgoyne's other brother was Andrew Randall Burgoyne (born Kingsbridge 1798).
Field Marshal Sir John Fox Burgoyne was born in 1782.
(I'm totally discounting the possibility that Sir John Fox Burgoyne's mum Susan Caulfield was a Burgoyne or that her affair was with one of our Devon Burgoynes rather than General Burgoyne, because it seems very remote! And also I have no Caulfields or Burnestones showing up in my DNA martches!!!!!)
So I can't see Maria's story being true, myself. But I have been known to get a bit bamboozled with how these relationships work, and exactly what constitutes a "great uncle" (could it be a great-great uncle, or once removed or something?). I'll happily let others school me if so

I do think there may have been a Burgoyne family tendency to claim high-born kin. My Burgoynes certainly have form in that area. Ancestral folklore goes that our Irish-based Spencers are allegedly blue bloods who are related somehow to Winston Churchill (could be true but it's got to be an incredibly tangential relationship if so, and although it was a commonly voiced claim, there is the elephantine absence of evidence in the room). I don't know why they couldn't be satisfied with having an ancestor who brought gaslight to Holywood and built the Married Soldiers' Quarters at Dundalk. Let alone a Professor of Electro-Medicine and Therapeutics.

)
While you are here .... could we please speak somewhere offline about the possibility of me securing a copy of key pages from the Burgoyne family bible? I would love to have another copy somewhere for posterity

I am sorry i couldn't help snare that Fox!
Please stay in touch, and all the very best!

Grant