He was the first Governor of the Cape Colony and sat in the House of Lords as an Irish representative peer from 1804 to 1839.

His eldest son, the fourth Earl,[6][7] sat in the House of Lords as an Irish Representative Peer from 1877 to 1898.

Today the titles are held by his only son, the seventh Earl, who succeeded in 1980.

The family's lineage can be traced to Captain Andrew Alexander, of Errigal, County Donegal, who was granted lands at Ballyclose near Limavady, County Londonderry, in 1663 and was later attainted by the parliament called by James II in Dublin in 1689.

[9] The style Viscount Alexander is used as a courtesy title for the Earl's eldest son and heir apparent.