From the longer biography on Wikipedia 
John Alcock (c. 1430 – 1 October 1500) was an English churchman.
He was the first president of the Council of the Marches in Wales from 1473 to 1500. He twice held the office of Lord Chancellor, once from June 1475 to September 1475 and then again from October 1485 to March 1487
Alcock was appointed to the Council in 1470 and became Master of the Rolls in 1471, soon after being appointed tutor to King Edward IV's eldest son, Prince Edward. After the King's death he was with Prince Edward and his younger brother when they were intercepted by Richard, Duke of Gloucester, at Stony Stratford. Alcock was arrested and removed from office but soon rejoined the Council. He was with King Richard III when he entered York in August 1483 and was a member of the English delegation that met the Scots at Nottingham.
Later Alcock was one of several clerics who openly canvassed the proposition that Henry Tudor marry Elizabeth of York. Appointed temporary Lord Chancellor he opened King Henry VII's first Parliament on 7 November 1485 and became one of the new king's most trusted servants.
Alcock died on 1 October 1500 and lies buried in the Alcock Chantry in Ely Cathedral.