an ancestor of my OH married for the second time a younger lady . He died and she then married his son from his first marriage'
Illegal according to the list but legally/openly registered in Winchester around the 1840s
Spring
If the marriage was by Banns in a church then although banns were intended as a security against unlawful marriages, the law gave clergymen no power to compel parties unknown to him to give any information as to their age, kindred, history or other circumstances. If the marriage was by ecclesiastical licence then the parties declared on oath that there was no legal impediment to the marriage, and that Canon Law was not being broken.
If the marriage was by Registrars Certificate then the parties had to declare on oath that there was no impediment of kindred or alliance, or other lawful hindrance, to the marriage. A marriage not meeting all the legal requirements in place at the time was and is invalid.
Stan