Defining family in Cator v Thynn

For centuries, English law recognised a category now largely confined to history: the bastard. At common law, an illegitimate child was filius nullius—the child of nobody. Such children could not inherit from their fathers on intestacy and were frequently excluded from family settlements and trusts designed to preserve wealth within a bloodline. Expressions such as ‘heirs of the body’, ‘lawful issue’ and ‘lawful descendants’ were common features of aristocratic settlements and trust instruments. Unless the settlor indicated otherwise, such language generally excluded those born outside marriage (Hill v Crook (1873) LR 6 HL 265).

The concept was not merely social but proprietary. Trusts became one of the principal mechanisms through which family wealth was preserved and transmitted across generations. Beneficial entitlement was often restricted to a narrowly defined family line, meaning that legitimacy could determine access to landed estates and substantial trust funds. Modern law no longer treats illegitimate children as legal outsiders.