He died in 1841 of an accidental morphine overdose; Helen continued to spend her summers at his family estate at Clandeboye in Ireland, which now belonged to Frederick.
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At seventeen, Helen was engaged to Commander Price Blackwood, youngest of three sons of Hans, Lord Dufferin, and Mehetabel Temple; owing to the deaths of his brothers he was to be the future Lord Dufferin, although his parents wanted him to marry more advantageously, mainly based on financial grounds.
The current Chairman of The Standing Council of Irish Chiefs and Chieftains is Dr. Hugo Ricciardi O'Neill, the current head of the Clandeboye O'Neill dynasty, from a branch of that family which has been in Portugal since the 18th century.