[1] Fanshawe succeeded as remembrancer of the exchequer on the death of his father in 1616, the post being held in trust for him until he was able to take up his duties in 1619.
In 1628 he was re-elected MP for Hertford and sat until 1629 when King Charles decided to rule without parliament for eleven years.
[3] He was commissioner of array for the king in 1641 and fought on the Royalist side at the Battle of Edgehill.
He had his property sequestrated, as orders for the sale of Fanshawe's goods were issued by the parliament on 29 June 1643, and on 1 January 1644 a committee was appointed to examine a report that Sir William Litton had concealed part of Fanshawe's property.
Lord Fanshawe died intestate at his town house in Hatton Garden, and was buried at Ware on 30 March 1665.