James Grenville, 1st Baron Glastonbury

James Grenville, 1st Baron Glastonbury, PC (6 July 1742 – 26 April 1825) of Butleigh Court, Somerset was a United Kingdom politician, who was a member of both houses of Parliament during his career.

Background Grenville was the eldest son of James Grenville MP (12 February 1715 – 14 September 1783) and a first cousin of George Nugent-Temple-Grenville, 1st Marquess of Buckingham. He was educated at Eton College and Christ Church, Oxford.

The Grenvilles were the most prominent aristocratic family in the south-eastern English county of Buckinghamshire in the 18th and early 19th centuries. For much of this time they supplied one of the two parliamentary representatives of Buckinghamshire and both of those from the town of Buckingham. The family produced some prominent national political figures, including two Prime Ministers (George Grenville and William Wyndham Grenville, 1st Baron Grenville). They were also related to William Pitt the Elder and William Pitt the Younger.

Career Grenville served as Member of Parliament for the Yorkshire borough of Thirsk 1766–1768. He sat for his family borough of Buckingham 1770–1790, from 1774 to 1780 in partnership with his twin brother, Richard. He then represented the county seat of Buckinghamshire 1790–1797.

He succeeded his father in 1783. As a politician he generally followed his family connection up to 1801 and after 1806, but between those years he continued to support William Pitt the Younger instead of becoming closer to Charles James Fox as most of his politically active Grenville relatives did.

He held junior ministerial office as a Lord of the Treasury March 1782 – March 1783. William Petty, 2nd Earl of Shelburne offered to make Grenville Chancellor of the Exchequer or Secretary at War, but he declined these appointments. He was sworn of the Privy Council on 26 December 1783. He was a member of the Board of Trade from 1784 until his death.

On 20 October 1797 he was created Baron Glastonbury. Lord Glastonbury never married and the title became extinct on his death in 1825. He left his estate to the bibliophile Thomas Grenville, with a remainder, including Butleigh Court, to a relative, the Reverend George Neville of Windsor, later Dean of Windsor, who then added the name of Grenville to his own.