Background
The son of Colonel J. F. Costello and both a namesake and kinsman of Dubhaltach Caoch Mac Coisdealbhaigh, Costello was born in Ireland.
The son of Colonel J. F. Costello and both a namesake and kinsman of Dubhaltach Caoch Mac Coisdealbhaigh, Costello was born in Ireland.
He was educated for the army at the Royal Military College, Sandhurst, and served for a short time in India, British North America, and the West Indies.
He left the army in 1828, and then passed some years in Paris, where he was introduced to Baron Cuvier, who employed him as a draughtsman in the preparation of his Règne animal. About 1838 he became foreign correspondent for the Morning Herald. In 1846 he became foreign correspondent of the Daily News.
And during the last twenty years of his life he held the post of sub-editor of the Examiner.