Certainly the "baronial St Maurs" died out in the male line in 1409 when their heir became Baron Zouche of Haryngworth, namely William la Zouche, 5th Baron Zouche (c. 1402 – 1462), whose son was William la Zouche, 6th Baron Zouche, 7th Baron St Maur (c. 1432 – 1468/69).