From the Wikipedia page
The Croyland Chronicle (or "Crowland Chronicle") is an important, if not always reliable, primary source for English medieval history, in particular the late fifteenth century. It was written at the Benedictine Abbey of Croyland, in Lincolnshire, England, off and on from 655 to 1486, and its first author claimed to be 'Ingulph' or 'Ingulf' of Croyland'. This author is now referred to as Pseudo-Ingulf.
The part that covers the years 1459–1486 was written in April 1486 (after Henry Tudor had become Henry VII of England) by someone who had access to information from the court of Richard III—described as being a doctor of canon law and member of Edward IV's council. Some historians believe that author was John Russell, Bishop of Lincoln, who was Richard's Chancellor for most of his reign (until Richard dismissed him on July 24, 1485) but who now wanted to please the new king Henry. Others conclude the work was written by a monk of Crowland who has edited a secular source.
Over the years, there has been confusion between the second and third continuators, and the fourth continuator claims not to know the identity of the third. It is, in fact, the second continuator (covering the period 1459–1486) who claims to be writing in April 1486, and, sure enough, this section ends with the marriage of Henry VII of England and Elizabeth of York and the rebellion that followed. This date ties in with the survival of a copy of Titulus Regius in the text, and Russell is known to have been at Crowland during April, 1486.