Sir Francis Thornhagh (1617-1647) was an English soldier, High Sheriff and MP.
He was born the son of the East Retford MP and High Sheriff of Nottinghamshire Sir Francis Thornhagh of Fenton, Lincolnshire and educated at Lincoln school and Magdalen College, Cambridge, before entering the Inner Temple in 1636. He was appointed High Sheriff of Nottinghamshire for 1637.
He enlisted to fight in the Netherlands under the Earl of Essex, returning in 1640.
He married Elizabeth, daughter and coheiress of John St. Andrew, of Gotham. They lived on St. Mary's Hill, Nottingham and at his wife's home, Rushcliffe Hall, Gotham.
He was made a Justice of the Peace in 1642. During the Civil War he was, like his father, a Parliamentarian, served on the shire committee and was appointed Lieutenant-Colonel of his father's horse regiment. On his father's death he succeeded to his estates at Fenton and elsewhere, together with his colonelcy. He was wounded at the relief of Gainsborough in 1643 and again at Newark later that year. After the Parliamentary victory at the Battle of Rowton Heath near Chester, he was voted a 1000 pounds prize for his gallantry. He was then elected as MP for East Retford, taking his seat when the town was freed.
After the end of the Civil War, a Scottish army under the Duke of Hamilton marched south and Thornhagh marched under Oliver Cromwell to meet them. He was killed near Chorley during mopping up operations after the Battle of Preston (1648).
He left an only son John, who also became Sheriff of Nottinghamshire and MP for East Retford (and Nottinghamshire).