Crisis magazine has a short biography.
most famous for being present to the king inside a pie, he also was a spy, a Captain on the Royalist side of the revolution, killed a man in a dual, and at age 25 was captured by Barbary pirates and a slave in North Africa for 25 years...before being rescued.
Curiously, in his years of slavery, Jeffrey had grown in spurts to 48 inches, which is not uncommon for those with pituitary deficiency, so he could no longer make much of a living as a curiosity.
The article remembers a few other people of short stature. Charles I was only 4 ft 8 inches; the poet Alexander Pope was only 4 foot (and also a Catholic). Both probably genetic or lack of growth from disease/nutrition.