It was created in 1822 for Francis Needham, 12th Viscount Kilmorey, a General in the British Army and former Member of Parliament for Newry.

His son, the second Viscount, represented Newcastle-under-Lyme in Parliament and supported King Charles I during the Civil War.

His younger son, the fourth Viscount (who succeeded his elder half-brother), also fought as a Royalist in the Civil War.

The Needham estate or Mourne Park is now owned by the Anley family, descendants of the 4th Earl of Kilmorey.

The heir apparent is the present holder's son Robert Francis John Needham, Viscount Newry and Mourne (born 1966).