| Office: | Member of Parliament for Fowey |
| Term Start: | 1768 |
| Term End: | 1774 |
| Predecessor: | Philip Rashleigh Hon. Robert Boyle-Walsingham |
| Successor: | Philip Rashleigh The Lord Shuldham |
| Office1: | High Sheriff of Devon |
| Term Start1: | 1759 |
| Term End1: | 1760 |
| Predecessor1: | Peter Comyns |
| Successor1: | Arscott Bickford |
| Birth Date: | 1732 |
| Education: | Eton College |
| Alma Mater: | Trinity College, Cambridge |
| Parents: | James Heywood Mary Elton |
| Spouse: | Catherine Hartopp |
| Children: | 6 |
| Relations: | Sir Abraham Elton, 2nd Baronet (grandfather) |
James Modyford Heywood (c1729 – 22 March 1798) was an English Member of Parliament for Fowey, plantation owner in Jamaica, and Lord of the Admiralty.
Heywood was the only son of James Heywood (c1684–1738), of Maristow (near Roborough in Devon) and Jamaica, and the former Mary Elton (1706–1755), daughter of Sir Abraham Elton, 2nd Baronet of Clevedon Court, MP for Bristol and Taunton.[1] His paternal grandparents were Col. Peter Heywood and Grace (Modyford) Heywood (daughter of Elizabeth (Stanning) Modyford and Sir James Modyford, 1st Baronet, Deputy-governor of Jamaica).[2] His sister, Lucy Heywood, married Sir Robert Throckmorton, 4th Baronet.[3]
Heywood succeeded to his father's estates in 1738, including Heywood Hall in St. Mary, Jamaica.[4] He was educated at Eton between 1742 and 1747 and entered Trinity College, Cambridge on 8 June 1747, aged 17.
Heywood served as High Sheriff of Devon in 1759. After a contest, Heywood was returned for Fowey on the Edgcumbe interest in 1768, although no vote by him is recorded before February 1774. In 1770 Thomas Davenport wrote to the Duke of Portland, that "Heywood would have Administration support at the next election." There is no record of his having spoken in the House and he did not stand again for Parliament.[5]
Heywood served as Lord of the Admiralty from December 1783 to March 1784,.[5] under his brother-in-law, Richard Howe, 1st Earl Howe (who became First Lord of the Admiralty in January 1783 during the Earl of Shelburne's ministry, resigning in April 1783 when the Duke of Portland came to power and being re-appointed in December 1783 under the Younger Pitt's first ministry.[6]
Before his death, Heywood sold his Jamaican estate, Heywood Hall (and the enslaved people on it), to Donald Campbell for £18,000.[4]
In 1755 Heywood married Catherine Hartopp, daughter and co-heiress of Gen. Chiverton Hartopp of Welby, Nottinghamshire, the Lt. Governor of Plymouth.[7] Her sister, Mary Hartopp, was the wife of Richard Howe, 1st Earl Howe.[8] Together, Catherine and James were the parents of one son and five daughters,[5] including:
Heywood died on 22 March 1798 and was buried at St Botolph's, Shenleybury, Shenley.[16] After his death, he instructed that his English estates be sold to fund the trusts under his will.[4] Accordingly, Maristow House was sold to Manasseh Masseh Lopes (the son of a rich plantation owner, whose family later gained the title of Baron Roborough),[17] reputedly for £100,000.[4]