Facts in Persuasion

As the oldest male heir to Baron Eliot, he would inherit the title.  Titles and land went to male rather than female heirs, even if the males were nephews or cousins.

Tattersall's is a famous club for betting on horse races, founded by a horse auctioneer Richard Tattersall.

Somersetshire is a county south west of London.  One of the important characteristics of Austen's work is her realism, which includes placing the action of her novels in specific counties and towns or cities. Many locations are actual, but some are fictional, such as Sir Walter Eliot's country home, Kellynch Hall.