] About a month ago, I posted a list of Officers of the 12th Light Dragoons (Captain Frederick Tilney’s regiment in "Northanger Abbey"). I thought there might be a name there, with a direct connection to Jane Austen, which would explain why she made such a direct reference. (A friend or family member who served in that unit, perhaps.)

As Linden pointed out the only really obvious one is Lindsay / Linsey James Bertie. He was born in Portsmouth in 1795, son of Admiral Sir Albemarle Bertie (who helped captue Mauritius) and Emma Heywood. It's possible that Francis Austen or Charles Austen (JA's sailor brothers) knew him. (Albemarle certainly had a Willoughby reporting to him).

Rather than the Ancasters, this branch of the Berties (though still related) were descended from the Earls of Lindsay. Lindsay James Bertie was about a 3rd or 4th cousin of Jane Austen's eldest niece, Anna Austen (daughter of James Austen and Anne Mathew).

To be fair, in view of his late birth date I think it's more likely to be coincidence but I will go through the list again against my database.

For those interested, here is a link to the Ashford letter written seven years after JA's death by Lindsay James Bertie's sister, Emma.