Hello! I’m rewatching the Tudors TV show, & one of the points brought up w/ Henry VIII is that should Catherine of Aragon acquiesce to the Papal grant of annulment, their daughter Mary would be considered illegitimate. But modern Catholic ecclesiastical law recognizes that in the case of annulled marriages, the relationship was still a putative marriage & thus any offspring of the union are legitimate. When did that change happen? Was it always there and Henry et al not aware of it?
This was actually still the case at that time. Henry didn't necessarily have to make Mary illegitimate; he initially was willing to keep her as heir presumptive and to keep her in the line of succession once he had a son with Anne, as he thought he would. He became intransigent after years of wrangling and fighting to achieve his goals, and Mary's own stubbornness in acknowledging that her parents' marriage hadn't been real didn't help.