Thomas QUIN, aged 18, born Armagh parish, Armagh city, Armagh county, Ireland, joined the Royal Artillery on 02 August 1778.
Others who joined the "Detachment of 5 Company" and were "inlisted" by Corporal PURCELL were
Thomas GIBSON, 16, weaver; Thomas McCANN, 24, weaver; Alexander BOYD, 21, labourer; Alexander NICHOLSON, 22, weaver; Thomas MAJOR, 21, weaver; William GORMAN, 17, weaver; Benjamin SCOTT, 19, weaver; and Robert SPENCER, 18.
(This list is from WO 54 / 269, held at The National Archives, Kew, London.)
Thomas QUIN was posted to Plymouth Dock, Devon, England, where he married Charlotte MASON in 1781.
They are believed to be the parents of John Thomas QUIN, born Plymouth ~1782, and William QUIN, born Woolwich, Kent, England, in 1787.
Woolwich was the headquarters of the Royal Artillery. Thomas was posted there in 1783, but at some point was sent to Nova Scotia. He died in Halifax in 1792 (presumably aged around 32). I do not know what became of his wife Charlotte QUIN, nor their son William.
Their son John Thomas QUIN joined the Royal Artillery in Woolwich as a drummer boy, aged 11, in 1793. He remained in the Royal Artillery most of his life, retiring aged 65, and dying shortly thereafter.
I have details of John Thomas QUIN's marriage, wife's ancestry, their children, children's marriages, and further descendants. (Some went to the Caribbean, some to the USA, many remained in England, and some descendants are in Canada.)
I'm happy to correspond with other members of this QUIN family, especially if you have details of earlier generations in Armagh.