De Lancey came of a distinguished American loyalist family of Huguenot descent.
De Lancey declined a contest in 1802 and was disgraced two years later when the commissioners of military inquiry reported that he could not account for considerable sums of money entrusted to him. No further action was then taken despite pressure from John Calcraft in the House, as the only fault imputed was negligence. The property he had purchased and improved in Surrey was, however, seized by government to meet his liabilities in 1806.
