According to Lart18 he died on 2 Feb, 1722 (i.e., as a baby), but this is clearly an error. Jean is named as a son in the will of Charles (March, 1722/3), and on page 116 of the London Huguenot Society's publication of the Registers of the French Non-Conformist Churches of Lucy Lane and Peter Street, Dublin, it is stated that Jean Boileau died 1 Feb 1772 at the age of 50 and was buried on the 3rd at the Green (thanks to Sidney Holdrege for this information).