He was commissioned to create public works commemorating the IRA and other republicans, including the Custom House Memorial (Dublin), the East Mayo Brigade IRA Memorial, the Republican Memorial (Crossmaglen), and the Ballyseedy Memorial (Kerry).
Winn-Allanson was the elder son of George Allanson-Winn, 1st Baron Headley, by his second wife Jane Blennerhassett, daughter and co-heiress of Arthur Blennerhassett, of Ballyseedy, County Kerry.
After her death in October 1774 he married secondly Jane Blennerhassett, daughter and co-heiress of Arthur Blennerhassett, of Ballyseedy, County Kerry, in 1783.