Sorry Adam, but in post #1 you have James Winch baptised in 1840 and no idea who his parents were, but later you say that the parents, established, were James and Margaret. I’m a bit perplexed.
As Sarah was born in Hayes, perhaps this could be your James. James Winch baptised Hayes 1804 father Richard mother Elizabeth. Do you have something that states he was definitely born in Harefield?
I have finally found the burial of Margaret Winch (Anc has transcribed her as Wench) 1846 at St Mary the Virgin Harefield so born c1766 Margaret Winch is on the 1841 census at Copper Mills but FMP has her age as 40 - it is not clear, and I think I says 70 HO107 piece655 book7 folio9 page10
I have found the niece Harriet Winch in 1841 in Denham HO107 piece60 book3 folio10 page14 James Winch b1781 Buckinghamshire - chimney sweep Sarah Winch b1781 not born in county John Winch b1811 Buckinghamshire (who is named as Harriet's father on the m/c) - chimney sweep Sarah Winch b1821 Harriet Winch b1831 James Winch b1835 Shame no family relationships are shown which would help. So many James and Sarah Winches
On wikitree and rootschat it seems Sarah is Sarah Salter and a marriage at Hanover Square in 1826 and more children including Caroline, Eliza, George, James and others.
I did find the marriage of a James Winch and Sarah Salter in the ebook of St George Hanover Square Register on 21st May 1826.
I saw that but could not find a baptism in Hayes for a Sarah Salter. There is also a marriage of a James Wynch to Margaret Rice at St James Picadilly on 26/8/1798 both were OTP - the witnesses both had the surname Morgan so no help there either
Sorry for not replying to this thread - I appear not to have been notified! James’ birthplace was Harefield, as I found two aunts of Caroline, both of whom were christened in Harefield to James Sr. and Margaret. James Jr. and Sarah married at St. George Hanover Square, and bizarrely most of their children married outside of the Uxbridge area, including at that particular church. So to clarify: I know nothing of Sarah Salter from Hayes (b. ca. 1796) but I see that has been covered (thanks MollyMay) Nor do I know anything of James Winch Sr. and Margaret Winch of Harefield, other than the christening dates for their children