Interesting.
One of the important questions is which POD could be best.
Any marriage of an English king prior to the 1320s could work.
Alternatively you have a French king inheriting.
Or via rebellion etc. E.g. Louis Capet the unnumbered temporary King of England, son of Philippe II Auguste.
I found two other possibilities last evening:
POD in the 1450s.
- Henri VI dies in or soon after 1453 and Richard of York seizes the throne, imprisoning his widow and son.
- He defeats the French and regains Normandy and maybe a few other Northern territories.
- Dauphin Louis is killed in battle and Richard later deposes Charles VII and is crowned King of France.
- Charles's youngest son Charles, Duke of Berry, becomes the French pretender and gains support in Southern parts of France, while in Scotland, James II, as John of Gaunt's descendant, claims the English throne - Margaret Beaufort's wedding to Edmund Tudor having been butterflied by Henry VI's death.
POD in the 1210s.
- Philippe II Auguste's son Louis is crowned King of England
- John doesn't contract dysentery and eventually manages to flee to Aquitaine with his wife and children.
- John and Raymond VI of Toulouse become allies.
- Later, Alexander II, not too fond of having a neighbour holding both England and Northern France, claims England - either as Margaret of Wessex's descendant or maybe in Eleanor of Brittany's name (but this is unlikely, he'd first have to free her and Louis's going to keep an eye on her, since her claim's stronger than his own wife's).