He was of Pounsley, near Blackboys, Framfield, Sussex. He was baptised at Framfield, 28 January 1776 (Seamer).
He (Joseph Semar of Heathfield) married Phoebe Ashdown at Chiddingly, after banns, 12 April 1797. Phoebe Ashdown was the daughter of William Ashdown and Ann (nee Smith), and baptised 15 August 1775 at Heathfield.
He (labourer of Jevington) purchased a messuage and 2 gardens in Jevington from William Levett of Jevington in April 1805 and sold it (as victualler) for £640 in April 1810 to John Gorring of Seaford, brewer, who immediately granted Joseph Seymour a 7 year lease. The property was then known as the Eight Bells.
In 1811, he purchased the copyhold of the manor of Jevington.
On 23 October 1811, William Catt surrendered the tenement known as The Horsecroft (4½ a) in Jevington to Joseph Seymour of Jevington, victualler, for £215.
In 1817 he had built the windmill at Willingdon (later known as Polegate Windmill).
In 1819 he (a miller) purchased The Butts, from the estate of Edmund Cooper and immediately sold part of it to John Swaine Kine of Folkington, miller.
On 3 May 1826, Joseph took on, for three years, an apprentice, Henry Thomas, aged 17, a son of James Thomas, miller, of Bexhill.
On 7 August 1833, Joseph was a guardian of Thomas John Kine, aged 15, who was apprenticed for 4 years to Edward Beeny of Herstmonceux, miller.
Joseph Seymour built Polegate Watermill, originally known as the Lower Watermill, in 1833. This, together with Wannock Watermill, was owned by the Seymour and Thomas families. The mill went into decline in the 1960s due to housing development in the area, which brought the risk of flooding. The mill was put up for sale in 1972, but with no buyers coming forward, it was demolished in 1974.
On 29 October 1834, Walter Funnell, aged 20, a son of Samuel Funnell of Chiddingly, farmer, was apprenticed to Joseph for 3 years.
In about 1840 he purchased The Parks and The Greenlands in Jevington.
Joseph Seymour purchased Wannock Watermill in 1840. Wannock Watermill ceased grinding corn in 1918 and was demolished in 1956 due to its poor condition.
In the 1841 census of Willingdon, Joseph was aged 65, a miller. Phoebe was aged 65 and with them were John Chapman (41), an agricultural labourer, Stephen Seymour (28) an agricultural labourer, Nathan Seymour (21) a miller's journeyman, John Rippington (17), a miller's apprentice, Joseph Seymour (20) an agricultural Labourer, and two servants, Naomi Butler (19) and Louisa Porter (11). All were born in Sussex except Louisa Porter.
Joseph Seymour died in the September quarter of 1845, in the district of Eastbourne.
His will was proved 5 March 1846 and dated 15 May 1843. He is described as a miller and farmer. His executors were John Gorringe, farmer of Eastbourne and Thomas Noakes, farmer of Wannock and his estate was of value under £6000. Under his will he bequeathed £25 a year for life to his widow Phoebe from the income received from the messuage where he then dwelt, with the barn, granary, stable, flour room, lodges, yards, orchard and ground belonging to it. Also several pieces of land bought from Richard Tutt at or near Foul Ride Green, Willingdon, comprising eight acre meadow, five acre arable, the Barn Field meadow and Drimble Orchard. Also seven pieces of land bought from Thomas Luck in Willingdon, a piece of land of 2 roods and 27 perches in the East Wish in Willingdon, 2 acres in Willingdon late Rippington's, before English's, before Tutt's and a messuage at Wannock in Jevington, late Brook's. The freeholds were left to his executors and the rents and profits of the freeholds and copyholds to his daughter Charlotte, the wife of James Manser during her life and then when sold the money to be equally distributed between her children or else the children of his son Joseph; subject to two mortgages of £500 to John Hoper and Thomas Baker (deceased) and a bequest of £500 between George Porter and Louisa Porter, the children of his daughter Sophia (the wife of James William French) by her first husband, John Porter (deceased). He further bequeathed £25 a year for life to his widow Phoebe from the income received from the New Water Corn Mill in Willingdon with the messuage and garden adjoining, Rough Croft field, late Cooper's, the messuage, barn, garden, and orchard of 4½ acres, late Chaser's and held from the manor of Willingdon, the pieces of land called the Specks of seven acres with the millpond, the piece of land called Horscroft of 4½ acres in Jevington held from the manor of Jevington, the piece of land called the Butts of 3 acres held from the manor of Jevington Rectory, the water corn mill called Wannock Mill and 41 acres of arable land and meadow belonging to it in Jevington and Folkington parishes. The freeholds were left to his executors and the rents and profits to his daughter Phillis (the wife of Henry Thomas) for her life and when sold the moneys divided between the children of Phillis Thomas subject to a mortgage of £1000 plus interest to Thomas Baker (deceased), a mortgage of £650 to Thomas Kine and the annuity paid to widow Philadelphia Noakes, and the sum of £1000 to be invested for the benefit of his daughter Hannah (the wife of William Rose) for life then the capital to her children subject to the payment of bills of exchange for £190 on behalf of William Rose. He further bequeathed the land called the Great Brinkhurst and the windmill in Willingdon and the land called the Little Brinkhurst in Willingdon, adjoining the road from Lewes to Eastbourne, and the messuage in which his son now lives with the Bakehouse, late Denman's, before Dunbrill's in Willingdon and the house purchased from Samuel Douch in Willingdon, late Smith's, before Blackman's (for his wife Phoebe for life), the 2 acres that his son then used, late Newman's, to his son Joseph, subject to a mortgage of £500 to John Hoper. He gave £500 to Charlotte, £500 to be invested for the benefit of Sophia and then to her children by James William French or else to George and Louisa Porter, £500 to be invested for the benefit of his daughter Ruth, (the wife of John Neville Dunbrill the younger) and then the capital to her children, and £25 to Phoebe immediately. The residue to be divided between Joseph Seymour and Phillis Thomas.
This will was initially the only evidence for Joseph Seymour's children. However, the baptisms of three daughters, Sophia, Phillis and Ruth were later found at the Independent Non-Conformist Chapel, Heathfield.
In the 1851 census of Mewett Cottages, Willingdon, Phoebe was a widow, aged 76, born at Chiddingly. Phoebe was buried at Willingdon, 13 August 1853, aged 78.
Joseph and Phoebe's children were: