His eldest son , the sixth Duke , briefly represented Newark in the House of Commons .
He was a prominent politician and held office as Chief Secretary for Ireland , as Secretary of State for the Colonies and as Secretary of State for War .
politician 's eldest son , the sixth Duke , briefly represented Newark in the House of Commons .
He was a prominent politician and held office as Chief Secretary for Ireland , as Secretary of State for the Colonies and as Secretary of State for War .