What part, if any, he played in the Percy revolt of 1405 is not clear. However, he became a ringleader of the Southampton Plot in 1415, which aimed to murder King Henry V in Southampton before he sailed to France, and replace him with Edmund Mortimer, 5th Earl of March. However, Mortimer revealed the plot to the King, and the conspirators were promptly arrested and executed.
He married Alice Nevill, daughter of Ralph Nevill, 1st Earl of Westmoreland, c. 1401,by and they had eight children:
a daughter born c. 1410, married an Arundell
Margaret Grey born c. 1414, married Gerard Widdrington