Fanshawe was the fourth and youngest son of
Sir Henry Fanshawe, of
Ware Park,
Hertfordshire and his wife Elizabeth Smythe, daughter of
Thomas Smythe, of Ostenhanger Kent and was baptised at Ware on 12 June 1608. His father, who was
Remembrancer of the Exchequer, died in 1616. Fanshawe was admitted at
Jesus College, Cambridge in November 1623 and was admitted to
Inner Temple on 22 January 1626. He travelled on
the Continent, and in 1635 was Secretary to the Embassy at the Court of Spain. In 1638, he was Chargé d'Affaires there. He was an accomplished linguist, whose knowledge of "modern languages" like Spanish and Italian is said to have been a great advantage to him in his diplomatic career. ==Civil War==