The Chancellor of the Duchy of Lancaster is, in modern times, a ministerial office in the government of the United Kingdom that includes as part of its duties, the administration of the estates and rents of the Duchy of Lancaster.
Originally, the Chancellor was the chief officer in the daily management of the Duchy of Lancaster and the County Palatine of Lancaster (a county palatine merged into the Crown in 1399), but that estate is now run by a deputy, leaving the Chancellor to serve in effect as an additional Minister without Portfolio. The position has often been given to a junior Cabinet minister with responsibilities in a particular area of policy for which there is no department with an appropriate portfolio.
In 1491, the office of Vice-Chancellor of the County Palatine of Lancaster (Wikipedia page ) was created. The position is now held by a judge of the Chancery Division of the High Court, who sits in the north-west, and no longer appointed to that position as legal officer of the Duchy.
More information on the Wikipedia page