Complex sentence: Even after the council was disbanded in January 1380, he remained a central figure at court, participating in the negotiations for the king's marriage to Anne of Bohemia, and mediating in a conflict between John of Gaunt and Henry Percy, Earl of Northumberland.
Split into simpler sentences: Even after the council was disbanded in January 1380, he remained a central figure at court. He took part in the negotiations for the king's marriage to Anne of Bohemia, and also mediated in a conflict between John of Gaunt and Henry Percy, Earl of Northumberland.