Sidmouth was the son of Reverend William Leonard Addington , 2nd Viscount Sidmouth , eldest son of Prime Minister Henry Addington , 1st Viscount Sidmouth . The son of Reverend William Leonard Addington , 2nd Viscount Sidmouth , eldest son of Prime Minister Henry Addington , 1st Viscount Sidmouth .
Sidmouth merupakan anak kepada Pendeta William Leonard Addington, Viscount ke-2 Sidmouth, anak sulung kepada Perdana Menteri Henry Addington, Viscount ke-1 Sidmouth. Anak kepada Pendeta William Leonard Addington, 2 Viscount Sidmouth, anak sulung Perdana Menteri Henry Addington, 1 Viscount Sidmouth.