Erasmus Darwin was descended from a Lincolnshire family, and the first of his ancestors of whom we know anything was William Darwin, who possessed a small estate at Cleatham. He was also yeoman of the armoury of Greenwich to James I. and Charles I. This office was probably almost a sinecure, and certainly of very small value. He died in 1644, and we have reason to believe from gout. It is, therefore, probable that Erasmus, as well as many other members of the family, inherited from this William, or some of his predecessors, their strong tendency to gout; and it was an early attack of gout which made Erasmus a vehement advocate for temperance throughout his whole life.

The second William Darwin (born 1620) served as Captain-Lieutenant in Sir W. Pelham's troop of horse, and fought for the king. His estate was sequestrated by the Parliament, but he was afterwards pardoned on payment of a heavy fine. In a petition to Charles II. he speaks of his almost utter ruin from having adhered to the royal cause, and it appears that he had become a barrister. This circumstance probably led to his marrying the daughter of Erasmus Earle, Serjeant-at-law; and hence Erasmus Darwin derived his Christian name.

The eldest son from this marriage, William (born 1655), married the heiress of Robert Waring, of Wilsford, in the county of Nottingham. This lady also inherited the manor of Elston, which has remained ever since in the family.