The Moore family descends from Sir Garrett Moore, a staunch friend of Hugh O'Neill, the Great Earl of Tyrone, whose submission he facilitated, hosting the negotiations that led to the Treaty of Mellifont in 1603 and ending The Nine Years' War.

Charles was succeeded by his son Henry, the aforementioned third Viscount, who was raised to an earldom, as Earl of Drogheda, in 1661.

The latter died without surviving children at an early age and was succeeded by his younger brother, Edward, the fifth Earl, who had previously represented Dunleer in the Irish Parliament.

He was succeeded in the remaining titles by his second cousin once removed, Ponsonby Moore, who became the ninth Earl.

He was the great-grandson of the Honourable Ponsonby Moore, younger son of the fifth Earl and brother of the first Marquess.

In 1954 Henry was created Baron Moore, of Cobham in the County of Surrey, in the Peerage of the United Kingdom, which entitled him and his descendants to an automatic seat in the House of Lords.

The Honourable Robert Moore, younger son of the third Earl, represented County Louth and Belfast in the Irish Parliament.