Sir John Brownlow, 5th Bt, succeeded his father in 1701 at the age of only 11 years. The family estates were administered by his maternal grandmother until he came of age in 1711. His first wife was his cousin Eleanor Brownlow (d.1730), the co-heiress of Sir John's uncle the third Baronet. After the death of both his father-in-law and mother-in-law Belton House passed to the couple in 1721. He created a Baroque State bedroom in the house and added many architectural follies to the grounds. Sir John first entered politics in 1713 as member of parliament for Grantham. He stood unapposed as member for Lincolnshire in 1715, but returned as member for Grantham in the elections of 1722, 1727 and 1734. He was raised to the Peerage of Ireland as Baron Charleville in the County of Cork, and Viscount Tyrconnel in 1719. He died without descendants in 1754 at the age of 63, whereupon both the baronetcy and the peerages became extinct. The Brownlow estates, including Belton House, passed to his nephew Sir John Cust, 3rd Baronet (1718-1770), son of his sister Anne Brownlow, whose son was raised to the peerage as Baron Brownlow in 1776.